Add more details to error message (eclipse-jdt#4992)

Mention the name of the project that has the error in order to better
deal with it.

Author: fedejeanne

org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/ClasspathEntry.java

@@ -1843,7 +1843,7 @@ public static IJavaModelStatus validateClasspath(IJavaProject javaProject, IClas
 
 		IProject project = javaProject.getProject();
 		IPath projectPath= project.getFullPath();
-		String projectName = javaProject.getElementName();
+		final String projectName = javaProject.getElementName();
 
 		/* validate output location */
 		if (projectOutputLocation == null) {
@@ -2163,7 +2163,7 @@ public boolean isOK() {
 						if (hasTest && !hasMain) {
 							return new JavaModelStatus(IJavaModelStatusConstants.MAIN_ONLY_PROJECT_DEPENDS_ON_TEST_ONLY_PROJECT,
 									Messages.bind(Messages.classpath_main_only_project_depends_on_test_only_project,
-											new String[] { prereqProject.getElementName() }));
+											new String[] { projectName, prereqProject.getElementName() }));
 						}
 					}
 				}

org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/util/messages.properties

@@ -190,7 +190,7 @@ classpath_deprecated_variable = Classpath variable ''{0}'' in project ''{1}'' is
 classpath_invalidExternalAnnotationPath = Invalid external annotation path: ''{0}'' in project ''{1}'', for classpath entry ''{2}''
 classpath_testSourceRequiresSeparateOutputFolder=Test source folder ''{0}'' in project ''{1}'' must have a separate output folder
 classpath_testOutputFolderMustBeSeparateFromMainOutputFolders=Test source folder ''{0}'' in project ''{1}'' must have an output folder that is not also used for main sources
-classpath_main_only_project_depends_on_test_only_project=Project has only main sources but depends on project ''{0}'' which has only test sources.
+classpath_main_only_project_depends_on_test_only_project=Project ''{0}'' has only main sources but depends on project ''{1}'' which has only test sources.
 classpath_illegalAddExportsSystemModule=Exporting a package from system module ''{0}'' is not allowed with --release.