public boolean isIdentityField(Field f, Class<?> clazz) {
    return manager.defaultIsIdentityField(f, clazz);
  }
Controls what fields of a class that is auto serialized will be marked as pdx identity fields.
Override this method to customize what fields of an auto serialized class will be identity
fields. Identity fields are used when a {@link PdxInstance} computes its hash code and checks
to see if it is equal to another object.
<p>
The default implementation only marks fields that match an "#identity=" pattern as identity
fields.
<p>
This method is only called the first time it sees a new class. The result will be remembered
and used the next time the same class is seen.

@param f the field to test to see if it is an identity field.
@param clazz the original class being serialized that owns this field. Note that this field may
       have been inherited from a super class by this class. If you want to find the class that
       declared this field use {@link Field#getDeclaringClass()}.
@return true if the field should be marked as an identity field; false if not.
@since GemFire 6.6.2
geode-core/src/main/java/org/apache/geode/pdx/ReflectionBasedAutoSerializer.java