code: public ClientConnectionTimingsBuilder socketConnectEnd() {
          checkState(socketConnectStartTimeMicros >= 0, "socketConnectStart() is not called yet.");
          checkState(!socketConnectEndSet, "socketConnectEnd() is already called.");
          socketConnectEndNanos = System.nanoTime();
          socketConnectEndSet = true;
          return this;
      }
docs: Sets the time when the client ended to connect to a remote peer.
  
  @throws IllegalStateException if {@link #socketConnectStart()} is not invoked before calling this.