code: public boolean containsSignatureDef(
        java.lang.String key) {
      if (key == null) { throw new java.lang.NullPointerException(); }
      return internalGetSignatureDef().getMap().containsKey(key);
    }
docs: <pre>
  signature_def: Map from user supplied key for a signature to a single
  SignatureDef.
  </pre>
  
  <code>map&lt;string, .tensorflow.SignatureDef&gt; signature_def = 5;</code>