public java.lang.String getUserId() {
      java.lang.Object ref = userId_;
      if (!(ref instanceof java.lang.String)) {
        com.google.protobuf.ByteString bs = (com.google.protobuf.ByteString) ref;
        java.lang.String s = bs.toStringUtf8();
        userId_ = s;
        return s;
      } else {
        return (java.lang.String) ref;
      }
    }
<pre>
Required if
[allow_missing_ids][google.cloud.talent.v4.RequestMetadata.allow_missing_ids]
is unset or `false`.

A unique user identification string, as determined by the client.
To have the strongest positive impact on search quality
make sure the client-level is unique.
Obfuscate this field for privacy concerns before
providing it to the service.

Note that any improvements to the model for a particular tenant site rely
on this field being set correctly to a unique user ID.

The maximum number of allowed characters is 255.
</pre>

<code>string user_id = 3;</code>

@return The userId.
java-talent/proto-google-cloud-talent-v4/src/main/java/com/google/cloud/talent/v4/RequestMetadata.java