fixes #510 try to reproduce the issue but failed

Author: stevehu

src/test/java/com/networknt/schema/Issue510Test.java

@@ -0,0 +1,13 @@
+package com.networknt.schema;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.junit.jupiter.api.Test;
+
+public class Issue510Test {
+    @Test
+    public void testIssue510() {
+        ObjectMapper objectMapper = new ObjectMapper();
+        JsonSchemaFactory schemaFactory = JsonSchemaFactory.builder(JsonSchemaFactory.getInstance(SpecVersion.VersionFlag.V201909)).objectMapper(objectMapper).build();
+        System.out.println("schemaFactory = " + schemaFactory);
+    }
+}