Add explicit ClaimsValidator implementation check for custom claims (#343)

* Add explicit ClaimsValidator implementation check for custom claims Prevent user from misnaming or fat fingering the Validate() method implementation. * Update example_test.go --------- Co-authored-by: Christian Banse <oxisto@aybaze.com>

Author: epelc

example_test.go

@@ -124,6 +124,9 @@ type MyCustomClaims struct {
  jwt.RegisteredClaims
 }
 
+// Ensure we implement [jwt.ClaimsValidator] at compile time so we know our custom Validate method is used.
+var_ jwt.ClaimsValidator= (*MyCustomClaims)(nil)
+
 // Validate can be used to execute additional application-specific claims
 // validation.
 func (mMyCustomClaims) Validate() error {