fix: Do not report java.util.ConcurrentModificationException as violation (#116)

Author: pboos

openapi-validation-core/src/main/java/com/getyourguide/openapi/validation/core/exclusions/InternalViolationExclusions.java

@@ -17,7 +17,8 @@ public boolean isExcluded(OpenApiViolation violation) {
             || falsePositive406(violation)
             || falsePositiveRequestWith4xxResponse(violation)
             || customViolationExclusions.isExcluded(violation)
-            || oneOfMatchesMoreThanOneSchema(violation);
+            || oneOfMatchesMoreThanOneSchema(violation)
+            || isConcurrentModificationExceptionInLibrary(violation);
     }
 
     private static boolean oneOfMatchesMoreThanOneSchema(OpenApiViolation violation) {
@@ -55,4 +56,9 @@ private boolean falsePositive406(OpenApiViolation violation) {
         return violation.getResponseStatus().orElse(0) == 406
             && Rules.Response.STATUS_UNKNOWN.equals(violation.getRule());
     }
+
+    private boolean isConcurrentModificationExceptionInLibrary(OpenApiViolation violation) {
+        return "validation.response.body.schema.unknownError".equals(violation.getRule())
+            && violation.getMessage().contains("java.util.ConcurrentModificationException");
+    }
 }