support nulls in TextNode equals (#4379)

Author: pjfanning

src/main/java/com/fasterxml/jackson/databind/node/TextNode.java

@@ -1,6 +1,7 @@
 package com.fasterxml.jackson.databind.node;
 
 import java.io.IOException;
+import java.util.Objects;
 
 import com.fasterxml.jackson.core.*;
 import com.fasterxml.jackson.core.io.CharTypes;
@@ -164,13 +165,16 @@ public boolean equals(Object o)
         if (o == this) return true;
         if (o == null) return false;
         if (o instanceof TextNode) {
-            return ((TextNode) o)._value.equals(_value);
+            TextNode otherNode = (TextNode) o;
+            return Objects.equals(otherNode._value, _value);
         }
         return false;
     }
 
     @Override
-    public int hashCode() { return _value.hashCode(); }
+    public int hashCode() {
+        return Objects.hashCode(_value);
+    }
 
     @Deprecated // since 2.10
     protected static void appendQuoted(StringBuilder sb, String content)

src/test/java/com/fasterxml/jackson/databind/node/TextNodeTest.java

@@ -1,5 +1,7 @@
 package com.fasterxml.jackson.databind.node;
 
+import static org.junit.Assert.assertNotEquals;
+
 public class TextNodeTest extends NodeTestBase
 {
     public void testText()
@@ -36,4 +38,19 @@ public void testText()
         assertFalse(TextNode.valueOf("false").asBoolean(true));
         assertFalse(TextNode.valueOf("false").asBoolean(false));
     }
+
+    public void testEquals()
+    {
+        assertEquals(new TextNode(null), new TextNode(null));
+        assertEquals(new TextNode("abc"), new TextNode("abc"));
+        assertNotEquals(new TextNode(null), new TextNode("def"));
+        assertNotEquals(new TextNode("abc"), new TextNode("def"));
+        assertNotEquals(new TextNode("abc"), new TextNode(null));
+    }
+
+    public void testHashCode()
+    {
+        assertEquals(0, new TextNode(null).hashCode());
+        assertEquals("abc".hashCode(), new TextNode("abc").hashCode());
+    }
 }