public int hashCode()
        {
            final int prime = 31;
            int result = 1;
            result = prime * result
                    + ((animals == null) ? 0 : animals.hashCode());
            result = prime * result
                    + ((largestAnimal == null) ? 0 : largestAnimal.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