code: public com.google.iam.v1.PolicyDelta getPolicyDelta() {
      return policyDelta_ == null ? com.google.iam.v1.PolicyDelta.getDefaultInstance() : policyDelta_;
    }
docs: <pre>
  Policy delta between the original policy and the newly set policy.
  </pre>
  
  <code>.google.iam.v1.PolicyDelta policy_delta = 2;</code>