oas 3.1 dereference - don't dereference $anchor

Author: frantuma

modules/swagger-parser-v3/src/main/java/io/swagger/v3/parser/reference/OpenAPI31Traverser.java

@@ -1056,6 +1056,9 @@ public void mergeSchemas(Schema source, Schema target) {
         if (source.getMaxLength() != null){
             target.setMaxLength(source.getMaxLength());
         }
+        if (source.get$anchor() != null){
+            target.set$anchor(source.get$anchor());
+        }
         if (source.get$comment() != null){
             target.set$comment(source.get$comment());
         }

modules/swagger-parser-v3/src/main/java/io/swagger/v3/parser/reference/ReferenceVisitor.java

@@ -198,6 +198,7 @@ public Schema resolveSchemaRef(Schema visiting, String ref, List<String> inherit
             baseURI = ReferenceUtils.resolve(ref, baseURI);
             baseURI = ReferenceUtils.toBaseURI(baseURI);
             Reference reference = null;
+            boolean isAnchor = false;
             if (this.reference.getReferenceSet().containsKey(baseURI)) {
                 reference = this.reference.getReferenceSet().get(baseURI);
             }
@@ -222,9 +223,12 @@ public Schema resolveSchemaRef(Schema visiting, String ref, List<String> inherit
                 if (evaluatedNode == null) {
                     throw new RuntimeException("Could not find " + fragment + " in contents of " + ref);
                 }
+                isAnchor = true;
             }
             Schema resolved = openAPITraverser.deserializeFragment(evaluatedNode, Schema.class, ref, fragment, reference.getMessages());
-
+            if (isAnchor) {
+                resolved.$anchor(null);
+            }
             ReferenceVisitor visitor = new ReferenceVisitor(reference, openAPITraverser, this.visited, this.visitedMap);
             return openAPITraverser.traverseSchema(resolved, visitor, inheritedIds);
         } catch (Exception e) {

modules/swagger-parser-v3/src/test/resources/3.1.0/dereference/schema/$anchor-external/dereferenced.json

@@ -11,7 +11,6 @@
             "type" : "string"
           },
           "profile" : {
-            "$anchor" : "user-profile",
             "properties" : {
               "firstName" : {
                 "type" : "string"