public Builder setSessionId(java.lang.String value) {
      if (value == null) {
        throw new NullPointerException();
      }
      sessionId_ = value;
      bitField0_ |= 0x00000002;
      onChanged();
      return this;
    }
<pre>
Required if
[allow_missing_ids][google.cloud.talent.v4beta1.RequestMetadata.allow_missing_ids]
is unset or `false`.

A unique session identification string. A session is defined as the
duration of an end user's interaction with the service over a certain
period.
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 session ID.

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

<code>string session_id = 2;</code>

@param value The sessionId to set.
@return This builder for chaining.
java-talent/proto-google-cloud-talent-v4beta1/src/main/java/com/google/cloud/talent/v4beta1/RequestMetadata.java