HV-1470 Switching to warning instead of error when validatedBy is empty

Author: marko-bekhta

annotation-processor/src/main/java/org/hibernate/validator/ap/internal/checks/ConstraintValidatorCheck.java

@@ -47,7 +47,7 @@ public Set<ConstraintCheckIssue> checkAnnotationType(TypeElement element, Annota
 		if ( !( atLeastOneValidatorGiven || constraintHelper.isComposedConstraint( element ) ) ) {
 
 			return CollectionHelper.asSet(
-					ConstraintCheckIssue.error(
+					ConstraintCheckIssue.warning(
 							element,
 							constraintMirror,
 							"CONSTRAINT_TYPE_WITHOUT_VALIDATOR"

annotation-processor/src/main/resources/org/hibernate/validator/ap/ValidationProcessorMessages.properties

@@ -12,7 +12,7 @@ ATVALID_NOT_ALLOWED_AT_PRIMITIVE_FIELD=Fields of a primitive type must not annot
 ATVALID_NOT_ALLOWED_AT_METHOD_RETURNING_PRIMITIVE_TYPE=Methods returning a primitive type must not annotated with @Valid.
 CONSTRAINT_TYPE_WITH_MISSING_OR_WRONG_RETENTION=Constraint annotation types must be annotated with @Retention(RUNTIME).
 CONSTRAINT_TYPE_WITH_WRONG_TARGET=Constraint annotation types must have at least one of the element types FIELD, METHOD, TYPE or ANNOTATION_TYPE as target.
-CONSTRAINT_TYPE_WITHOUT_VALIDATOR=For non-composed constraints a validator implementation must be specified using @Constraint#validatedBy().
+CONSTRAINT_TYPE_WITHOUT_VALIDATOR=No constraint validators are declared in the 'validatedBy()' attribute of the constraint declaration, make sure that they are declared either programmatically, in the XML configuration or via the service loader.
 CONSTRAINT_TYPE_MUST_DECLARE_MESSAGE_MEMBER=Constraint annotation types must declare a member 'String message()'.
 RETURN_TYPE_MUST_BE_STRING=Return type of constraint annotation type member 'message()' must be 'String'.
 CONSTRAINT_TYPE_MUST_DECLARE_GROUPS_MEMBER=Constraint annotation types must declare a member 'Class<?>[] groups() default {}'.

annotation-processor/src/test/java/org/hibernate/validator/ap/AnnotationTypeValidationTest.java

@@ -104,10 +104,10 @@ public void testThatConstraintAnnotationTypeWithoutValidatorCausesCompilationErr
 		boolean compilationResult =
 				compilerHelper.compile( new ConstraintValidationProcessor(), diagnostics, sourceFile1, sourceFile2 );
 
-		assertFalse( compilationResult );
+		assertTrue( compilationResult );
 		assertThatDiagnosticsMatch(
 				diagnostics,
-				new DiagnosticExpectation( Kind.ERROR, 24 )
+				new DiagnosticExpectation( Kind.WARNING, 24 )
 		);
 	}