TestUtil: include entire diagnostic on failure

This way we get the line number

tooling/metamodel-generator/src/test/java/org/hibernate/jpamodelgen/test/util/TestUtil.java

@@ -181,7 +181,7 @@ public class TestUtil {
 	public static void assertNoCompilationError(List<Diagnostic<?>> diagnostics) {
 		for ( Diagnostic<?> diagnostic : diagnostics ) {
 			if ( diagnostic.getKind().equals( Diagnostic.Kind.ERROR ) ) {
-				fail( "There was a compilation error during annotation processing:\n" + diagnostic.getMessage( null ) );
+				fail( "There was a compilation error during annotation processing:\n" + diagnostic );
 			}
 		}
 	}