public Builder setExpireTime(com.google.protobuf.Timestamp value) {
      if (expireTimeBuilder_ == null) {
        if (value == null) {
          throw new NullPointerException();
        }
        expiration_ = value;
        onChanged();
      } else {
        expireTimeBuilder_.setMessage(value);
      }
      expirationCase_ = 2;
      return this;
    }
<pre>
Desired expiration time of the access token. This value must
be at most 24 hours in the future. If a value is not specified, the
token's expiration time will be set to a default value of 1 hour in the
future.
</pre>

<code>.google.protobuf.Timestamp expire_time = 2;</code>
java-workstations/proto-google-cloud-workstations-v1beta/src/main/java/com/google/cloud/workstations/v1beta/GenerateAccessTokenRequest.java