As described in the Oracle "Non-Standard Options" documentation, this HotSpot option turns on strict class-file format checks. For compatibility, this option is also supported by the Eclipse OpenJ9™ VM.
Oracle recommend that you use this flag when you are developing new code because stricter checks will become the default in future releases.
Note: You cannot use this setting in conjunction with -XX:+ClassRelationshipVerifier.
By default, strict format checks are disabled.