### Question:
ResourceReferencesValidator implements ConstraintValidator<ValidResourceReferences, Map<String, ClientReferenceableFile>>, ValidationErrorDescriptorBuilder { @Override public boolean isValid(Map<String, ClientReferenceableFile> value, ConstraintValidatorContext context) { return findInvalidReferences(value).isEmpty(); }  @Override void initialize(ValidResourceReferences constraintAnnotation); @Override boolean isValid(Map<String, ClientReferenceableFile> value, ConstraintValidatorContext context); @Override ErrorDescriptor build(ConstraintViolation violation);  }### Answer:
@Test public void isValid_null_valid() { assertTrue(validator.isValid(null, context)); }
@Test public void isValid_mapWithFileReference_valid() { assertTrue(validator.isValid(correctValue, context)); }
@Test public void isValid_mapWithFileResource_invalid() { assertFalse(validator.isValid(invalidValue, context)); }