ERROR: parameter [topic_type] is not a valid package resource name

[sbergmair]

I have a ros topic that publishes from roscore (ros noetic).
The message (VelocityPub.msg) is at follows:

geometry_msgs/Vector3 diffVector
float64 hz

I try to subscribe on this topic using rosjava and this implemented message interface

public interface VelocityPub extends Message {
    String _TYPE = "package/of/velocity_pub/VelocityPub";
    String _DEFINITION = "geometry_msgs/Vector3 diffVector\nfloat64 hz\n";

    geometry_msgs.Vector3 getDiffVector();

    void setDiffVector(geometry_msgs.Vector3 var1);

    double getHz();

    void setHz(double var1);
}

But with running this, I get following error and don*t know where to search for the solution:

6203 [pool-1-thread-13] INFO  ternal.node.topic.DefaultSubscriber  - Subscriber registration failed: Subscriber<Topic<TopicIdentifier</Sim_Wand_0/velocity>, TopicDescription<package/of/velocity_pub/VelocityPub, 188c9752023b4c633ca60c07200a3c47>>>
11210 [pool-1-thread-73] ERROR .ros.internal.node.client.Registrar  - Exception caught while communicating with master.
org.ros.exception.RemoteException: ERROR: parameter [topic_type] is not a valid package resource name
	at org.ros.internal.node.response.Response.fromListChecked(Response.java:115)
	at org.ros.internal.node.client.MasterClient.registerSubscriber(MasterClient.java:110)
	at org.ros.internal.node.client.Registrar$5$1.call(Registrar.java:203)
	at org.ros.internal.node.client.Registrar$5$1.call(Registrar.java:200)
	at org.ros.internal.node.client.Registrar.callMaster(Registrar.java:111)
	at org.ros.internal.node.client.Registrar.access$100(Registrar.java:51)
	at org.ros.internal.node.client.Registrar$5.call(Registrar.java:200)
	at org.ros.internal.node.client.Registrar$5.call(Registrar.java:196)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
	at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at java.base/java.lang.Thread.run(Thread.java:829)

I can't find the error in the project and where it gets thrown.
Hope you can help

Thanks in advance!