Remove empty hamcrest-core 2.x from 'JUnit 4/5' classpath container

Since hamcrest version 2 the 'hamcrest-core' artifact only exists to
redirect to the new 'hamcrest' artifact containing all of hamcrest.
Therefore 'hamcrest-core' does only contains meteadata but no classes.
For the 'JUnit 4/5' classpath container it is therefore useless in
version 2 and later.

References:
- https://hamcrest.org/JavaHamcrest/distributables.html#previous-versions-of-hamcrest
- https://github.com/hamcrest/JavaHamcrest/releases/tag/v2.1

org.eclipse.jdt.junit.core/src/org/eclipse/jdt/internal/junit/buildpath/BuildPathSupport.java

@@ -304,9 +304,6 @@ public boolean accept(File dir, String name) {
 	public static final JUnitPluginDescription JUNIT4_PLUGIN= new JUnitPluginDescription(
 			"org.junit", new VersionRange("[4.13.0,5.0.0)"), null, "org.junit_4.*.jar", "org.junit.source", "source-bundle/", JUnitPreferencesConstants.JUNIT4_JAVADOC); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$ //$NON-NLS-5$
 
-	private static final JUnitPluginDescription HAMCREST_CORE_PLUGIN= new JUnitPluginDescription(
-			"org.hamcrest.core", new VersionRange("[2.2.0,3.1.0)"), null, "org.hamcrest.core_2.*.jar", "org.hamcrest.core.source", "source-bundle/", JUnitPreferencesConstants.HAMCREST_CORE_JAVADOC); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$ //$NON-NLS-5$
-
 	private static final JUnitPluginDescription HAMCREST_PLUGIN= new JUnitPluginDescription(
 			"org.hamcrest", new VersionRange("[2.2.0,3.1.0)"), null, "org.hamcrest_2.*.jar", "org.hamcrest.source", "source-bundle/", JUnitPreferencesConstants.HAMCREST_JAVADOC); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$ //$NON-NLS-5$
 
@@ -421,13 +418,6 @@ public static IClasspathEntry getJUnit4as3LibraryEntry() {
 		return JUNIT4_AS_3_PLUGIN.getLibraryEntry();
 	}
 
-	/**
-	 * @return the org.hamcrest.core library, or <code>null</code> if not available
-	 */
-	public static IClasspathEntry getHamcrestCoreLibraryEntry() {
-		return HAMCREST_CORE_PLUGIN.getLibraryEntry();
-	}
-
 	/**
 	 * @return the org.hamcrest library, or <code>null</code> if not available
 	 */

org.eclipse.jdt.junit.core/src/org/eclipse/jdt/internal/junit/buildpath/JUnitContainerInitializer.java

@@ -121,7 +121,6 @@ private static JUnitContainer getNewContainer(IPath containerPath, IClasspathAtt
 		case JUNIT4:
 			entriesList.add(BuildPathSupport.getJUnit4LibraryEntry());
 			entriesList.add(BuildPathSupport.getHamcrestLibraryEntry());
-			entriesList.add(BuildPathSupport.getHamcrestCoreLibraryEntry());
 			break;
 		case JUNIT5:
 			boolean vintage = isVintage(attributes);
@@ -145,7 +144,6 @@ private static JUnitContainer getNewContainer(IPath containerPath, IClasspathAtt
 				entriesList.add(BuildPathSupport.getJUnit4LibraryEntry());
 			}
 			entriesList.add(BuildPathSupport.getHamcrestLibraryEntry());
- 			entriesList.add(BuildPathSupport.getHamcrestCoreLibraryEntry());
 			// errors will be reported above
 			entriesList.removeIf(e -> e == null);
 			break;