NPE due to concurrency bug #392: Make JsonSchemaRef more thread-safe; Removed unused members and constructor (#393)

Author: Keymaster65

src/main/java/com/networknt/schema/JsonSchemaRef.java

@@ -28,23 +28,12 @@
 
 public class JsonSchemaRef {
 
-    private JsonSchema schema;
-    private ValidationContext validationContext;
-    private String refValue;
-
-    public JsonSchemaRef(ValidationContext validationContext, String refValue) {
-        this.validationContext = validationContext;
-        this.refValue = refValue;
-    }
+    private final JsonSchema schema;
 
     public JsonSchemaRef(JsonSchema schema) {
         this.schema = schema;
     }
 
-    public void set(JsonSchema schema) {
-        this.schema = schema;
-    }
-
     public Set<ValidationMessage> validate(JsonNode node, JsonNode rootNode, String at) {
         return schema.validate(node, rootNode, at);
     }

src/main/java/com/networknt/schema/RefValidator.java

@@ -95,10 +95,9 @@ static JsonSchemaRef getRefSchema(JsonSchema parentSchema, ValidationContext val
             if (node != null) {
                 JsonSchemaRef ref = validationContext.getReferenceParsingInProgress(refValueOriginal);
                 if (ref == null) {
-                    ref = new JsonSchemaRef(validationContext, refValue);
+                    final JsonSchema schema = new JsonSchema(validationContext, refValue, parentSchema.getCurrentUri(), node, parentSchema);
+                    ref = new JsonSchemaRef(schema);
                     validationContext.setReferenceParsingInProgress(refValueOriginal, ref);
-                    JsonSchema ret = new JsonSchema(validationContext, refValue, parentSchema.getCurrentUri(), node, parentSchema);
-                    ref.set(ret);
                 }
                 return ref;
             }