Improved handling for unknown keywords

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

@@ -18,12 +18,14 @@
 
 import java.lang.reflect.InvocationTargetException;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
+import java.util.concurrent.ConcurrentHashMap;
 
 import org.apache.commons.lang3.StringUtils;
 import org.slf4j.Logger;
@@ -36,7 +38,7 @@ public class JsonMetaSchema {
 
     private static final Logger logger = LoggerFactory
             .getLogger(JsonMetaSchema.class);
-
+    private static Map<String, String> UNKNOWN_KEYWORDS = new ConcurrentHashMap<String, String>();
 
     private static class DraftV4 {
         private static String URI = "http://json-schema.org/draft-04/schema#";
@@ -76,6 +78,15 @@ public static JsonMetaSchema getInstance() {
                     .idKeyword(DRAFT_4_ID)
                     .addFormats(BUILTIN_FORMATS)
                     .addKeywords(ValidatorTypeCode.getNonFormatKeywords())
+                    // keywords that may validly exist, but have no validation aspect to them
+                    .addKeywords(Arrays.asList(
+                            new NonValidationKeyword("$schema"),
+                            new NonValidationKeyword("id"),
+                            new NonValidationKeyword("title"), 
+                            new NonValidationKeyword("description"), 
+                            new NonValidationKeyword("default"),
+                            new NonValidationKeyword("definitions")
+                    ))
                     .build();
         }
     }
@@ -221,7 +232,10 @@ public Optional<JsonValidator> newValidator(ValidationContext validationContext,
         try {
             Keyword kw = keywords.get(keyword);
             if (kw == null) {
-                logger.warn("Unknown keyword " + keyword);
+                if (!UNKNOWN_KEYWORDS.containsKey(keyword)) {
+                    UNKNOWN_KEYWORDS.put(keyword, keyword);
+                    logger.warn("Unknown keyword " + keyword + " - you should define your own Meta Schema. If the keyword is irrelevant for validation, just use a NonValidationKeyword");
+                }
                 return Optional.empty();
             }
             return Optional.of(kw.newValidator(schemaPath, schemaNode, parentSchema, validationContext));

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

@@ -214,8 +214,11 @@ private boolean idMatchesSourceUrl(JsonMetaSchema metaSchema, JsonNode schema, U
         if (id == null || id.isEmpty()) {
             return false;
         }
-        logger.info("Matching " + id + " to " + schemaUrl.toString());
-        return id.equals(schemaUrl.toString());
+        boolean result = id.equals(schemaUrl.toString());
+        if (logger.isDebugEnabled()) {
+            logger.debug("Matching " + id + " to " + schemaUrl.toString() + ": " + result);
+        }
+        return result;
 
     }
 

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

@@ -0,0 +1,33 @@
+package com.networknt.schema;
+
+import java.util.Collections;
+import java.util.Set;
+
+import com.fasterxml.jackson.databind.JsonNode;
+
+/**
+ * Used for Keywords that have no validation aspect, but are part of the metaschema.
+ */
+public class NonValidationKeyword extends AbstractKeyword {
+
+    private static final class Validator extends AbstractJsonValidator {
+        private Validator(String keyword) {
+            super(keyword);
+        }
+
+        @Override
+        public Set<ValidationMessage> validate(JsonNode node, JsonNode rootNode, String at) {
+            return Collections.emptySet();
+        }
+    }
+
+    public NonValidationKeyword(String keyword) {
+        super(keyword);
+    }
+
+    @Override
+    public JsonValidator newValidator(String schemaPath, JsonNode schemaNode, JsonSchema parentSchema,
+            ValidationContext validationContext) throws JsonSchemaException, Exception {
+        return new Validator(getValue());
+    }
+}