public java.lang.String getKey() {
      java.lang.Object ref = key_;
      if (!(ref instanceof java.lang.String)) {
        com.google.protobuf.ByteString bs = (com.google.protobuf.ByteString) ref;
        java.lang.String s = bs.toStringUtf8();
        key_ = s;
        return s;
      } else {
        return (java.lang.String) ref;
      }
    }
<pre>
A unique key for this elementary stream. The key must be 1-63
characters in length. The key must begin and end with a letter (regardless
of case) or a number, but can contain dashes or underscores in between.
</pre>

<code>string key = 4;</code>

@return The key.
java-video-live-stream/proto-google-cloud-live-stream-v1/src/main/java/com/google/cloud/video/livestream/v1/ElementaryStream.java