public Builder mergeTtl(com.google.protobuf.Duration value) {
      if (ttlBuilder_ == null) {
        if (expirationCase_ == 3
            && expiration_ != com.google.protobuf.Duration.getDefaultInstance()) {
          expiration_ =
              com.google.protobuf.Duration.newBuilder((com.google.protobuf.Duration) expiration_)
                  .mergeFrom(value)
                  .buildPartial();
        } else {
          expiration_ = value;
        }
        onChanged();
      } else {
        if (expirationCase_ == 3) {
          ttlBuilder_.mergeFrom(value);
        } else {
          ttlBuilder_.setMessage(value);
        }
      }
      expirationCase_ = 3;
      return this;
    }
<pre>
Desired lifetime duration of the access token. This value must
be at most 24 hours. If a value is not specified, the token's lifetime
will be set to a default value of 1 hour.
</pre>

<code>.google.protobuf.Duration ttl = 3;</code>
java-workstations/proto-google-cloud-workstations-v1beta/src/main/java/com/google/cloud/workstations/v1beta/GenerateAccessTokenRequest.java