public int hashCode()
        {
            final int prime = 31;
            int result = super.hashCode();
            result = prime
                    * result
                    + ((someTigerField == null) ? 0 : someTigerField.hashCode());
            return result;
        }
Test for polymorphic serialization.
<p>
See {@link RuntimeDerivativeField} for details.

@author David Yu
@created Jan 15, 2011
protostuff-runtime/src/test/java/io/protostuff/runtime/PolymorphicSerializationTest.java