The exact toString output of an annotation is deliberately not specified; from java.lang.annotation.Annotation.toString(): Returns a string representation of this annotation. The details of the representation are implementation-dependent [...] Previously, the toString format of an annotation did not output certain information in a way that would be usable for a source code representation of an annotation, string values were not surrounded by double quote characters, array values were surrounded by brackets ("[]") rather than braces ("{}"), etc. As a behavioral change, the annotation output has been updated to be faithful to a source code representation of the annotation.