code: private List<OperationMessage> makePayloadOperations() {
      assert this.isLocked();
      assert !this.state.diffing;
      this.state.diffing = true;
      try {
        final List<OperationMessage> operations = new ArrayList<>();
        for (final AutoBean<? extends BaseProxy> currentView : this.state.editedProxies.values()) {
          final OperationMessage operation = this
              .makeOperationMessage(BaseProxyCategory.stableId(currentView), currentView, true).as();
          operations.add(operation);
        }
        return operations;
      } finally {
        this.state.diffing = false;
      }
    }
docs: Compute deltas for each entity seen by the context.
  <p>
  TODO(t.broyer): reduce payload size by only sending proxies that are directly referenced by
  invocation arguments or by other proxies. For backwards-compatibility with no-op requests and
  operation-only requests, only do so when there's at least one invocation (or we can choose to
  break backwards compatibility for those edge-cases).
  </p>