public java.lang.String getControlPlaneIp() {
      java.lang.Object ref = controlPlaneIp_;
      if (!(ref instanceof java.lang.String)) {
        com.google.protobuf.ByteString bs = (com.google.protobuf.ByteString) ref;
        java.lang.String s = bs.toStringUtf8();
        controlPlaneIp_ = s;
        return s;
      } else {
        return (java.lang.String) ref;
      }
    }
<pre>
Output only. The private IP address of the control plane for this
workstation cluster. Workstation VMs need access to this IP address to work
with the service, so make sure that your firewall rules allow egress from
the workstation VMs to this address.
</pre>

<code>string control_plane_ip = 16 [(.google.api.field_behavior) = OUTPUT_ONLY];</code>

@return The controlPlaneIp.
java-workstations/proto-google-cloud-workstations-v1/src/main/java/com/google/cloud/workstations/v1/WorkstationCluster.java