PDFBOX-6179: add equals and hash

git-svn-id: https://svn.apache.org/repos/asf/pdfbox/trunk@1932458 13f79535-47bb-0310-9956-ffa450edef68

Author: THausherr

pdfbox/src/main/java/org/apache/pdfbox/pdmodel/interactive/form/PDField.java

@@ -18,6 +18,7 @@
 
 import java.io.IOException;
 import java.util.List;
+import java.util.Objects;
 
 import org.apache.pdfbox.cos.COSArray;
 import org.apache.pdfbox.cos.COSBase;
@@ -475,4 +476,33 @@ public String toString()
         return getFullyQualifiedName() + "{type: " + getClass().getSimpleName() + " value: " +
                 getInheritableAttribute(COSName.V) + "}";
     }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public boolean equals (Object o)
+    {
+        if (o == this)
+        {
+            return true;
+        }
+
+        if (!(o instanceof PDField))
+        {
+            return false;
+        }
+
+        COSDictionary toBeCompared = ((PDField) o).getCOSObject();
+        return toBeCompared.equals(getCOSObject());
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public int hashCode()
+    {
+        return Objects.hash(dictionary);
+    }
 }