public boolean equals(Object obj)
        {
            if (this == obj)
                return true;
            if (obj == null)
                return false;
            if (getClass() != obj.getClass())
                return false;
            Zoo other = (Zoo) obj;
            if (animals == null)
            {
                if (other.animals != null)
                    return false;
            }
            else if (!animals.equals(other.animals))
                return false;
            if (largestAnimal == null)
            {
                if (other.largestAnimal != null)
                    return false;
            }
            else if (!largestAnimal.equals(other.largestAnimal))
                return false;
            return true;
        }
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