diff --git a/conjure-java-core/src/integrationInput/java/com/palantir/product/EmptyPathServiceRetrofit.java b/conjure-java-core/src/integrationInput/java/com/palantir/product/EmptyPathServiceRetrofit.java
index a6e24c965..b3a69c13d 100644
--- a/conjure-java-core/src/integrationInput/java/com/palantir/product/EmptyPathServiceRetrofit.java
+++ b/conjure-java-core/src/integrationInput/java/com/palantir/product/EmptyPathServiceRetrofit.java
@@ -9,6 +9,6 @@
 @Generated("com.palantir.conjure.java.services.Retrofit2ServiceGenerator")
 public interface EmptyPathServiceRetrofit {
     @GET("./")
-    @Headers("hr-path-template: /")
+    @Headers({"hr-path-template: /", "Accept: application/json"})
     Call<Boolean> emptyPath();
 }
diff --git a/conjure-java-core/src/integrationInput/java/com/palantir/product/EteServiceRetrofit.java b/conjure-java-core/src/integrationInput/java/com/palantir/product/EteServiceRetrofit.java
index 83e4f169c..78133fd5d 100644
--- a/conjure-java-core/src/integrationInput/java/com/palantir/product/EteServiceRetrofit.java
+++ b/conjure-java-core/src/integrationInput/java/com/palantir/product/EteServiceRetrofit.java
@@ -24,63 +24,63 @@
 @Generated("com.palantir.conjure.java.services.Retrofit2ServiceGenerator")
 public interface EteServiceRetrofit {
     @GET("./base/string")
-    @Headers("hr-path-template: /base/string")
+    @Headers({"hr-path-template: /base/string", "Accept: application/json"})
     Call<String> string(@Header("Authorization") AuthHeader authHeader);
 
     @GET("./base/integer")
-    @Headers("hr-path-template: /base/integer")
+    @Headers({"hr-path-template: /base/integer", "Accept: application/json"})
     Call<Integer> integer(@Header("Authorization") AuthHeader authHeader);
 
     @GET("./base/double")
-    @Headers("hr-path-template: /base/double")
+    @Headers({"hr-path-template: /base/double", "Accept: application/json"})
     Call<Double> double_(@Header("Authorization") AuthHeader authHeader);
 
     @GET("./base/boolean")
-    @Headers("hr-path-template: /base/boolean")
+    @Headers({"hr-path-template: /base/boolean", "Accept: application/json"})
     Call<Boolean> boolean_(@Header("Authorization") AuthHeader authHeader);
 
     @GET("./base/safelong")
-    @Headers("hr-path-template: /base/safelong")
+    @Headers({"hr-path-template: /base/safelong", "Accept: application/json"})
     Call<SafeLong> safelong(@Header("Authorization") AuthHeader authHeader);
 
     @GET("./base/rid")
-    @Headers("hr-path-template: /base/rid")
+    @Headers({"hr-path-template: /base/rid", "Accept: application/json"})
     Call<ResourceIdentifier> rid(@Header("Authorization") AuthHeader authHeader);
 
     @GET("./base/bearertoken")
-    @Headers("hr-path-template: /base/bearertoken")
+    @Headers({"hr-path-template: /base/bearertoken", "Accept: application/json"})
     Call<BearerToken> bearertoken(@Header("Authorization") AuthHeader authHeader);
 
     @GET("./base/optionalString")
-    @Headers("hr-path-template: /base/optionalString")
+    @Headers({"hr-path-template: /base/optionalString", "Accept: application/json"})
     Call<Optional<String>> optionalString(@Header("Authorization") AuthHeader authHeader);
 
     @GET("./base/optionalEmpty")
-    @Headers("hr-path-template: /base/optionalEmpty")
+    @Headers({"hr-path-template: /base/optionalEmpty", "Accept: application/json"})
     Call<Optional<String>> optionalEmpty(@Header("Authorization") AuthHeader authHeader);
 
     @GET("./base/datetime")
-    @Headers("hr-path-template: /base/datetime")
+    @Headers({"hr-path-template: /base/datetime", "Accept: application/json"})
     Call<OffsetDateTime> datetime(@Header("Authorization") AuthHeader authHeader);
 
     @GET("./base/binary")
-    @Headers("hr-path-template: /base/binary")
+    @Headers({"hr-path-template: /base/binary", "Accept: application/octet-stream"})
     @Streaming
     Call<ResponseBody> binary(@Header("Authorization") AuthHeader authHeader);
 
     @POST("./base/notNullBody")
-    @Headers("hr-path-template: /base/notNullBody")
+    @Headers({"hr-path-template: /base/notNullBody", "Accept: application/json"})
     Call<StringAliasExample> notNullBody(
             @Header("Authorization") AuthHeader authHeader, @Body StringAliasExample notNullBody);
 
     @GET("./base/optionalAliasOne")
-    @Headers("hr-path-template: /base/optionalAliasOne")
+    @Headers({"hr-path-template: /base/optionalAliasOne", "Accept: application/json"})
     Call<StringAliasExample> optionalAliasOne(
             @Header("Authorization") AuthHeader authHeader,
             @Query("queryParamName") Optional<StringAliasExample> queryParamName);
 
     @GET("./base/aliasTwo")
-    @Headers("hr-path-template: /base/aliasTwo")
+    @Headers({"hr-path-template: /base/aliasTwo", "Accept: application/json"})
     Call<NestedStringAliasExample> aliasTwo(
             @Header("Authorization") AuthHeader authHeader,
             @Query("queryParamName") NestedStringAliasExample queryParamName);
diff --git a/conjure-java-core/src/main/java/com/palantir/conjure/java/services/Retrofit2ServiceGenerator.java b/conjure-java-core/src/main/java/com/palantir/conjure/java/services/Retrofit2ServiceGenerator.java
index 784fa011a..bbb1ffd41 100644
--- a/conjure-java-core/src/main/java/com/palantir/conjure/java/services/Retrofit2ServiceGenerator.java
+++ b/conjure-java-core/src/main/java/com/palantir/conjure/java/services/Retrofit2ServiceGenerator.java
@@ -55,6 +55,7 @@
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 import javax.lang.model.element.Modifier;
+import javax.ws.rs.core.MediaType;
 import org.apache.commons.lang3.StringUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -67,6 +68,9 @@ public final class Retrofit2ServiceGenerator implements ServiceGenerator {
     private static final ClassName CALL_TYPE = ClassName.get("retrofit2", "Call");
     private static final String AUTH_HEADER_NAME = "Authorization";
 
+    private static final String JSON_MEDIA_TYPE = MediaType.APPLICATION_JSON;
+    private static final String OCTET_STREAM_MEDIA_TYPE = MediaType.APPLICATION_OCTET_STREAM;
+
     private static final Logger log = LoggerFactory.getLogger(Retrofit2ServiceGenerator.class);
 
     private final Set<FeatureFlags> featureFlags;
@@ -133,11 +137,18 @@ private MethodSpec generateServiceMethod(
                 .addModifiers(Modifier.PUBLIC, Modifier.ABSTRACT)
                 .addAnnotation(AnnotationSpec.builder(httpMethodToClassName(endpointDef.getHttpMethod().get().name()))
                         .addMember("value", "$S", "." + endpointPathWithoutRegex)
-                        .build())
-                .addAnnotation(AnnotationSpec.builder(ClassName.get("retrofit2.http", "Headers"))
-                        .addMember("value", "$S", "hr-path-template: " + endpointPathWithoutRegex)
                         .build());
 
+        AnnotationSpec.Builder headersBuilder = AnnotationSpec.builder(ClassName.get("retrofit2.http", "Headers"))
+                .addMember("value", "$S", "hr-path-template: " + endpointPathWithoutRegex);
+        endpointDef.getReturns().ifPresent(type -> {
+            String mediaType = type.accept(TypeVisitor.IS_BINARY)
+                    ? MediaType.APPLICATION_OCTET_STREAM
+                    : MediaType.APPLICATION_JSON;
+            headersBuilder.addMember("value", "$S", "Accept: " + mediaType);
+        });
+        methodBuilder.addAnnotation(headersBuilder.build());
+
         if (endpointDef.getReturns().map(type -> type.accept(TypeVisitor.IS_BINARY)).orElse(false)) {
             methodBuilder.addAnnotation(AnnotationSpec.builder(ClassName.get("retrofit2.http", "Streaming")).build());
         }
diff --git a/conjure-java-core/src/test/resources/test/api/TestServiceRetrofit.java.retrofit b/conjure-java-core/src/test/resources/test/api/TestServiceRetrofit.java.retrofit
index e895a6e78..688851a2d 100644
--- a/conjure-java-core/src/test/resources/test/api/TestServiceRetrofit.java.retrofit
+++ b/conjure-java-core/src/test/resources/test/api/TestServiceRetrofit.java.retrofit
@@ -36,44 +36,56 @@ import retrofit2.http.Streaming;
 public interface TestServiceRetrofit {
     /** Returns a mapping from file system id to backing file system configuration. */
     @GET("./catalog/fileSystems")
-    @Headers("hr-path-template: /catalog/fileSystems")
+    @Headers({"hr-path-template: /catalog/fileSystems", "Accept: application/json"})
     Call<Map<String, BackingFileSystem>> getFileSystems(
             @Header("Authorization") AuthHeader authHeader);
 
     @POST("./catalog/datasets")
-    @Headers("hr-path-template: /catalog/datasets")
+    @Headers({"hr-path-template: /catalog/datasets", "Accept: application/json"})
     Call<Dataset> createDataset(
             @Header("Authorization") AuthHeader authHeader,
             @Body CreateDatasetRequest request,
             @Header("Test-Header") String testHeaderArg);
 
     @GET("./catalog/datasets/{datasetRid}")
-    @Headers("hr-path-template: /catalog/datasets/{datasetRid}")
+    @Headers({"hr-path-template: /catalog/datasets/{datasetRid}", "Accept: application/json"})
     Call<Optional<Dataset>> getDataset(
             @Header("Authorization") AuthHeader authHeader,
             @Path("datasetRid") ResourceIdentifier datasetRid);
 
     @GET("./catalog/datasets/{datasetRid}/raw")
-    @Headers("hr-path-template: /catalog/datasets/{datasetRid}/raw")
+    @Headers({
+        "hr-path-template: /catalog/datasets/{datasetRid}/raw",
+        "Accept: application/octet-stream"
+    })
     @Streaming
     Call<ResponseBody> getRawData(
             @Header("Authorization") AuthHeader authHeader,
             @Path("datasetRid") ResourceIdentifier datasetRid);
 
     @GET("./catalog/datasets/{datasetRid}/raw-aliased")
-    @Headers("hr-path-template: /catalog/datasets/{datasetRid}/raw-aliased")
+    @Headers({
+        "hr-path-template: /catalog/datasets/{datasetRid}/raw-aliased",
+        "Accept: application/json"
+    })
     Call<ResponseBody> getAliasedRawData(
             @Header("Authorization") AuthHeader authHeader,
             @Path("datasetRid") ResourceIdentifier datasetRid);
 
     @GET("./catalog/datasets/{datasetRid}/raw-maybe")
-    @Headers("hr-path-template: /catalog/datasets/{datasetRid}/raw-maybe")
+    @Headers({
+        "hr-path-template: /catalog/datasets/{datasetRid}/raw-maybe",
+        "Accept: application/json"
+    })
     Call<Optional<ByteBuffer>> maybeGetRawData(
             @Header("Authorization") AuthHeader authHeader,
             @Path("datasetRid") ResourceIdentifier datasetRid);
 
     @GET("./catalog/datasets/{datasetRid}/string-aliased")
-    @Headers("hr-path-template: /catalog/datasets/{datasetRid}/string-aliased")
+    @Headers({
+        "hr-path-template: /catalog/datasets/{datasetRid}/string-aliased",
+        "Accept: application/json"
+    })
     Call<AliasedString> getAliasedString(
             @Header("Authorization") AuthHeader authHeader,
             @Path("datasetRid") ResourceIdentifier datasetRid);
@@ -84,7 +96,10 @@ public interface TestServiceRetrofit {
             @Header("Authorization") AuthHeader authHeader, @Body RequestBody input);
 
     @GET("./catalog/datasets/{datasetRid}/branches")
-    @Headers("hr-path-template: /catalog/datasets/{datasetRid}/branches")
+    @Headers({
+        "hr-path-template: /catalog/datasets/{datasetRid}/branches",
+        "Accept: application/json"
+    })
     Call<Set<String>> getBranches(
             @Header("Authorization") AuthHeader authHeader,
             @Path("datasetRid") ResourceIdentifier datasetRid);
@@ -95,27 +110,36 @@ public interface TestServiceRetrofit {
      * @deprecated use getBranches instead
      */
     @GET("./catalog/datasets/{datasetRid}/branchesDeprecated")
-    @Headers("hr-path-template: /catalog/datasets/{datasetRid}/branchesDeprecated")
+    @Headers({
+        "hr-path-template: /catalog/datasets/{datasetRid}/branchesDeprecated",
+        "Accept: application/json"
+    })
     @Deprecated
     Call<Set<String>> getBranchesDeprecated(
             @Header("Authorization") AuthHeader authHeader,
             @Path("datasetRid") ResourceIdentifier datasetRid);
 
     @GET("./catalog/datasets/{datasetRid}/branches/{branch}/resolve")
-    @Headers("hr-path-template: /catalog/datasets/{datasetRid}/branches/{branch}/resolve")
+    @Headers({
+        "hr-path-template: /catalog/datasets/{datasetRid}/branches/{branch}/resolve",
+        "Accept: application/json"
+    })
     Call<Optional<String>> resolveBranch(
             @Header("Authorization") AuthHeader authHeader,
             @Path("datasetRid") ResourceIdentifier datasetRid,
             @Path(value = "branch", encoded = true) String branch);
 
     @GET("./catalog/datasets/{datasetRid}/testParam")
-    @Headers("hr-path-template: /catalog/datasets/{datasetRid}/testParam")
+    @Headers({
+        "hr-path-template: /catalog/datasets/{datasetRid}/testParam",
+        "Accept: application/json"
+    })
     Call<Optional<String>> testParam(
             @Header("Authorization") AuthHeader authHeader,
             @Path("datasetRid") ResourceIdentifier datasetRid);
 
     @POST("./catalog/test-query-params")
-    @Headers("hr-path-template: /catalog/test-query-params")
+    @Headers({"hr-path-template: /catalog/test-query-params", "Accept: application/json"})
     Call<Integer> testQueryParams(
             @Header("Authorization") AuthHeader authHeader,
             @Body String query,
@@ -137,19 +161,19 @@ public interface TestServiceRetrofit {
             @Query("optionalEnd") Optional<ResourceIdentifier> optionalEnd);
 
     @GET("./catalog/boolean")
-    @Headers("hr-path-template: /catalog/boolean")
+    @Headers({"hr-path-template: /catalog/boolean", "Accept: application/json"})
     Call<Boolean> testBoolean(@Header("Authorization") AuthHeader authHeader);
 
     @GET("./catalog/double")
-    @Headers("hr-path-template: /catalog/double")
+    @Headers({"hr-path-template: /catalog/double", "Accept: application/json"})
     Call<Double> testDouble(@Header("Authorization") AuthHeader authHeader);
 
     @GET("./catalog/integer")
-    @Headers("hr-path-template: /catalog/integer")
+    @Headers({"hr-path-template: /catalog/integer", "Accept: application/json"})
     Call<Integer> testInteger(@Header("Authorization") AuthHeader authHeader);
 
     @POST("./catalog/optional")
-    @Headers("hr-path-template: /catalog/optional")
+    @Headers({"hr-path-template: /catalog/optional", "Accept: application/json"})
     Call<Optional<String>> testPostOptional(
             @Header("Authorization") AuthHeader authHeader, @Body Optional<String> maybeString);
 
diff --git a/conjure-java-core/src/test/resources/test/api/TestServiceRetrofit.java.retrofit_completable_future b/conjure-java-core/src/test/resources/test/api/TestServiceRetrofit.java.retrofit_completable_future
index 441723656..a3f071ea5 100644
--- a/conjure-java-core/src/test/resources/test/api/TestServiceRetrofit.java.retrofit_completable_future
+++ b/conjure-java-core/src/test/resources/test/api/TestServiceRetrofit.java.retrofit_completable_future
@@ -36,44 +36,56 @@ import retrofit2.http.Streaming;
 public interface TestServiceRetrofit {
     /** Returns a mapping from file system id to backing file system configuration. */
     @GET("./catalog/fileSystems")
-    @Headers("hr-path-template: /catalog/fileSystems")
+    @Headers({"hr-path-template: /catalog/fileSystems", "Accept: application/json"})
     CompletableFuture<Map<String, BackingFileSystem>> getFileSystems(
             @Header("Authorization") AuthHeader authHeader);
 
     @POST("./catalog/datasets")
-    @Headers("hr-path-template: /catalog/datasets")
+    @Headers({"hr-path-template: /catalog/datasets", "Accept: application/json"})
     CompletableFuture<Dataset> createDataset(
             @Header("Authorization") AuthHeader authHeader,
             @Body CreateDatasetRequest request,
             @Header("Test-Header") String testHeaderArg);
 
     @GET("./catalog/datasets/{datasetRid}")
-    @Headers("hr-path-template: /catalog/datasets/{datasetRid}")
+    @Headers({"hr-path-template: /catalog/datasets/{datasetRid}", "Accept: application/json"})
     CompletableFuture<Optional<Dataset>> getDataset(
             @Header("Authorization") AuthHeader authHeader,
             @Path("datasetRid") ResourceIdentifier datasetRid);
 
     @GET("./catalog/datasets/{datasetRid}/raw")
-    @Headers("hr-path-template: /catalog/datasets/{datasetRid}/raw")
+    @Headers({
+        "hr-path-template: /catalog/datasets/{datasetRid}/raw",
+        "Accept: application/octet-stream"
+    })
     @Streaming
     CompletableFuture<ResponseBody> getRawData(
             @Header("Authorization") AuthHeader authHeader,
             @Path("datasetRid") ResourceIdentifier datasetRid);
 
     @GET("./catalog/datasets/{datasetRid}/raw-aliased")
-    @Headers("hr-path-template: /catalog/datasets/{datasetRid}/raw-aliased")
+    @Headers({
+        "hr-path-template: /catalog/datasets/{datasetRid}/raw-aliased",
+        "Accept: application/json"
+    })
     CompletableFuture<ResponseBody> getAliasedRawData(
             @Header("Authorization") AuthHeader authHeader,
             @Path("datasetRid") ResourceIdentifier datasetRid);
 
     @GET("./catalog/datasets/{datasetRid}/raw-maybe")
-    @Headers("hr-path-template: /catalog/datasets/{datasetRid}/raw-maybe")
+    @Headers({
+        "hr-path-template: /catalog/datasets/{datasetRid}/raw-maybe",
+        "Accept: application/json"
+    })
     CompletableFuture<Optional<ByteBuffer>> maybeGetRawData(
             @Header("Authorization") AuthHeader authHeader,
             @Path("datasetRid") ResourceIdentifier datasetRid);
 
     @GET("./catalog/datasets/{datasetRid}/string-aliased")
-    @Headers("hr-path-template: /catalog/datasets/{datasetRid}/string-aliased")
+    @Headers({
+        "hr-path-template: /catalog/datasets/{datasetRid}/string-aliased",
+        "Accept: application/json"
+    })
     CompletableFuture<AliasedString> getAliasedString(
             @Header("Authorization") AuthHeader authHeader,
             @Path("datasetRid") ResourceIdentifier datasetRid);
@@ -84,7 +96,10 @@ public interface TestServiceRetrofit {
             @Header("Authorization") AuthHeader authHeader, @Body RequestBody input);
 
     @GET("./catalog/datasets/{datasetRid}/branches")
-    @Headers("hr-path-template: /catalog/datasets/{datasetRid}/branches")
+    @Headers({
+        "hr-path-template: /catalog/datasets/{datasetRid}/branches",
+        "Accept: application/json"
+    })
     CompletableFuture<Set<String>> getBranches(
             @Header("Authorization") AuthHeader authHeader,
             @Path("datasetRid") ResourceIdentifier datasetRid);
@@ -95,27 +110,36 @@ public interface TestServiceRetrofit {
      * @deprecated use getBranches instead
      */
     @GET("./catalog/datasets/{datasetRid}/branchesDeprecated")
-    @Headers("hr-path-template: /catalog/datasets/{datasetRid}/branchesDeprecated")
+    @Headers({
+        "hr-path-template: /catalog/datasets/{datasetRid}/branchesDeprecated",
+        "Accept: application/json"
+    })
     @Deprecated
     CompletableFuture<Set<String>> getBranchesDeprecated(
             @Header("Authorization") AuthHeader authHeader,
             @Path("datasetRid") ResourceIdentifier datasetRid);
 
     @GET("./catalog/datasets/{datasetRid}/branches/{branch}/resolve")
-    @Headers("hr-path-template: /catalog/datasets/{datasetRid}/branches/{branch}/resolve")
+    @Headers({
+        "hr-path-template: /catalog/datasets/{datasetRid}/branches/{branch}/resolve",
+        "Accept: application/json"
+    })
     CompletableFuture<Optional<String>> resolveBranch(
             @Header("Authorization") AuthHeader authHeader,
             @Path("datasetRid") ResourceIdentifier datasetRid,
             @Path(value = "branch", encoded = true) String branch);
 
     @GET("./catalog/datasets/{datasetRid}/testParam")
-    @Headers("hr-path-template: /catalog/datasets/{datasetRid}/testParam")
+    @Headers({
+        "hr-path-template: /catalog/datasets/{datasetRid}/testParam",
+        "Accept: application/json"
+    })
     CompletableFuture<Optional<String>> testParam(
             @Header("Authorization") AuthHeader authHeader,
             @Path("datasetRid") ResourceIdentifier datasetRid);
 
     @POST("./catalog/test-query-params")
-    @Headers("hr-path-template: /catalog/test-query-params")
+    @Headers({"hr-path-template: /catalog/test-query-params", "Accept: application/json"})
     CompletableFuture<Integer> testQueryParams(
             @Header("Authorization") AuthHeader authHeader,
             @Body String query,
@@ -137,19 +161,19 @@ public interface TestServiceRetrofit {
             @Query("optionalEnd") Optional<ResourceIdentifier> optionalEnd);
 
     @GET("./catalog/boolean")
-    @Headers("hr-path-template: /catalog/boolean")
+    @Headers({"hr-path-template: /catalog/boolean", "Accept: application/json"})
     CompletableFuture<Boolean> testBoolean(@Header("Authorization") AuthHeader authHeader);
 
     @GET("./catalog/double")
-    @Headers("hr-path-template: /catalog/double")
+    @Headers({"hr-path-template: /catalog/double", "Accept: application/json"})
     CompletableFuture<Double> testDouble(@Header("Authorization") AuthHeader authHeader);
 
     @GET("./catalog/integer")
-    @Headers("hr-path-template: /catalog/integer")
+    @Headers({"hr-path-template: /catalog/integer", "Accept: application/json"})
     CompletableFuture<Integer> testInteger(@Header("Authorization") AuthHeader authHeader);
 
     @POST("./catalog/optional")
-    @Headers("hr-path-template: /catalog/optional")
+    @Headers({"hr-path-template: /catalog/optional", "Accept: application/json"})
     CompletableFuture<Optional<String>> testPostOptional(
             @Header("Authorization") AuthHeader authHeader, @Body Optional<String> maybeString);
 
diff --git a/conjure-java-core/src/test/resources/test/api/TestServiceRetrofit.java.retrofit_listenable_future b/conjure-java-core/src/test/resources/test/api/TestServiceRetrofit.java.retrofit_listenable_future
index 1dcb742b9..c2db14cca 100644
--- a/conjure-java-core/src/test/resources/test/api/TestServiceRetrofit.java.retrofit_listenable_future
+++ b/conjure-java-core/src/test/resources/test/api/TestServiceRetrofit.java.retrofit_listenable_future
@@ -36,44 +36,56 @@ import retrofit2.http.Streaming;
 public interface TestServiceRetrofit {
     /** Returns a mapping from file system id to backing file system configuration. */
     @GET("./catalog/fileSystems")
-    @Headers("hr-path-template: /catalog/fileSystems")
+    @Headers({"hr-path-template: /catalog/fileSystems", "Accept: application/json"})
     ListenableFuture<Map<String, BackingFileSystem>> getFileSystems(
             @Header("Authorization") AuthHeader authHeader);
 
     @POST("./catalog/datasets")
-    @Headers("hr-path-template: /catalog/datasets")
+    @Headers({"hr-path-template: /catalog/datasets", "Accept: application/json"})
     ListenableFuture<Dataset> createDataset(
             @Header("Authorization") AuthHeader authHeader,
             @Body CreateDatasetRequest request,
             @Header("Test-Header") String testHeaderArg);
 
     @GET("./catalog/datasets/{datasetRid}")
-    @Headers("hr-path-template: /catalog/datasets/{datasetRid}")
+    @Headers({"hr-path-template: /catalog/datasets/{datasetRid}", "Accept: application/json"})
     ListenableFuture<Optional<Dataset>> getDataset(
             @Header("Authorization") AuthHeader authHeader,
             @Path("datasetRid") ResourceIdentifier datasetRid);
 
     @GET("./catalog/datasets/{datasetRid}/raw")
-    @Headers("hr-path-template: /catalog/datasets/{datasetRid}/raw")
+    @Headers({
+        "hr-path-template: /catalog/datasets/{datasetRid}/raw",
+        "Accept: application/octet-stream"
+    })
     @Streaming
     ListenableFuture<ResponseBody> getRawData(
             @Header("Authorization") AuthHeader authHeader,
             @Path("datasetRid") ResourceIdentifier datasetRid);
 
     @GET("./catalog/datasets/{datasetRid}/raw-aliased")
-    @Headers("hr-path-template: /catalog/datasets/{datasetRid}/raw-aliased")
+    @Headers({
+        "hr-path-template: /catalog/datasets/{datasetRid}/raw-aliased",
+        "Accept: application/json"
+    })
     ListenableFuture<ResponseBody> getAliasedRawData(
             @Header("Authorization") AuthHeader authHeader,
             @Path("datasetRid") ResourceIdentifier datasetRid);
 
     @GET("./catalog/datasets/{datasetRid}/raw-maybe")
-    @Headers("hr-path-template: /catalog/datasets/{datasetRid}/raw-maybe")
+    @Headers({
+        "hr-path-template: /catalog/datasets/{datasetRid}/raw-maybe",
+        "Accept: application/json"
+    })
     ListenableFuture<Optional<ByteBuffer>> maybeGetRawData(
             @Header("Authorization") AuthHeader authHeader,
             @Path("datasetRid") ResourceIdentifier datasetRid);
 
     @GET("./catalog/datasets/{datasetRid}/string-aliased")
-    @Headers("hr-path-template: /catalog/datasets/{datasetRid}/string-aliased")
+    @Headers({
+        "hr-path-template: /catalog/datasets/{datasetRid}/string-aliased",
+        "Accept: application/json"
+    })
     ListenableFuture<AliasedString> getAliasedString(
             @Header("Authorization") AuthHeader authHeader,
             @Path("datasetRid") ResourceIdentifier datasetRid);
@@ -84,7 +96,10 @@ public interface TestServiceRetrofit {
             @Header("Authorization") AuthHeader authHeader, @Body RequestBody input);
 
     @GET("./catalog/datasets/{datasetRid}/branches")
-    @Headers("hr-path-template: /catalog/datasets/{datasetRid}/branches")
+    @Headers({
+        "hr-path-template: /catalog/datasets/{datasetRid}/branches",
+        "Accept: application/json"
+    })
     ListenableFuture<Set<String>> getBranches(
             @Header("Authorization") AuthHeader authHeader,
             @Path("datasetRid") ResourceIdentifier datasetRid);
@@ -95,27 +110,36 @@ public interface TestServiceRetrofit {
      * @deprecated use getBranches instead
      */
     @GET("./catalog/datasets/{datasetRid}/branchesDeprecated")
-    @Headers("hr-path-template: /catalog/datasets/{datasetRid}/branchesDeprecated")
+    @Headers({
+        "hr-path-template: /catalog/datasets/{datasetRid}/branchesDeprecated",
+        "Accept: application/json"
+    })
     @Deprecated
     ListenableFuture<Set<String>> getBranchesDeprecated(
             @Header("Authorization") AuthHeader authHeader,
             @Path("datasetRid") ResourceIdentifier datasetRid);
 
     @GET("./catalog/datasets/{datasetRid}/branches/{branch}/resolve")
-    @Headers("hr-path-template: /catalog/datasets/{datasetRid}/branches/{branch}/resolve")
+    @Headers({
+        "hr-path-template: /catalog/datasets/{datasetRid}/branches/{branch}/resolve",
+        "Accept: application/json"
+    })
     ListenableFuture<Optional<String>> resolveBranch(
             @Header("Authorization") AuthHeader authHeader,
             @Path("datasetRid") ResourceIdentifier datasetRid,
             @Path(value = "branch", encoded = true) String branch);
 
     @GET("./catalog/datasets/{datasetRid}/testParam")
-    @Headers("hr-path-template: /catalog/datasets/{datasetRid}/testParam")
+    @Headers({
+        "hr-path-template: /catalog/datasets/{datasetRid}/testParam",
+        "Accept: application/json"
+    })
     ListenableFuture<Optional<String>> testParam(
             @Header("Authorization") AuthHeader authHeader,
             @Path("datasetRid") ResourceIdentifier datasetRid);
 
     @POST("./catalog/test-query-params")
-    @Headers("hr-path-template: /catalog/test-query-params")
+    @Headers({"hr-path-template: /catalog/test-query-params", "Accept: application/json"})
     ListenableFuture<Integer> testQueryParams(
             @Header("Authorization") AuthHeader authHeader,
             @Body String query,
@@ -137,19 +161,19 @@ public interface TestServiceRetrofit {
             @Query("optionalEnd") Optional<ResourceIdentifier> optionalEnd);
 
     @GET("./catalog/boolean")
-    @Headers("hr-path-template: /catalog/boolean")
+    @Headers({"hr-path-template: /catalog/boolean", "Accept: application/json"})
     ListenableFuture<Boolean> testBoolean(@Header("Authorization") AuthHeader authHeader);
 
     @GET("./catalog/double")
-    @Headers("hr-path-template: /catalog/double")
+    @Headers({"hr-path-template: /catalog/double", "Accept: application/json"})
     ListenableFuture<Double> testDouble(@Header("Authorization") AuthHeader authHeader);
 
     @GET("./catalog/integer")
-    @Headers("hr-path-template: /catalog/integer")
+    @Headers({"hr-path-template: /catalog/integer", "Accept: application/json"})
     ListenableFuture<Integer> testInteger(@Header("Authorization") AuthHeader authHeader);
 
     @POST("./catalog/optional")
-    @Headers("hr-path-template: /catalog/optional")
+    @Headers({"hr-path-template: /catalog/optional", "Accept: application/json"})
     ListenableFuture<Optional<String>> testPostOptional(
             @Header("Authorization") AuthHeader authHeader, @Body Optional<String> maybeString);