public String getMessageGroupId() {
        return this.messageGroupId;
    }
<p>
This parameter applies only to FIFO (first-in-first-out) queues.
</p>
<p>
The tag that specifies that a message belongs to a specific message group. Messages that belong to the same
message group are processed in a FIFO manner (however, messages in different message groups might be processed
out of order). To interleave multiple ordered streams within a single queue, use <code>MessageGroupId</code>
values (for example, session data for multiple users). In this scenario, multiple consumers can process the
queue, but the session data of each user is processed in a FIFO fashion.
</p>
<ul>
<li>
<p>
You must associate a non-empty <code>MessageGroupId</code> with a message. If you don't provide a
<code>MessageGroupId</code>, the action fails.
</p>
</li>
<li>
<p>
<code>ReceiveMessage</code> might return messages with multiple <code>MessageGroupId</code> values. For each
<code>MessageGroupId</code>, the messages are sorted by time sent. The caller can't specify a
<code>MessageGroupId</code>.
</p>
</li>
</ul>
<p>
The maximum length of <code>MessageGroupId</code> is 128 characters. Valid values: alphanumeric characters and
punctuation <code>(!"#$%&amp;'()*+,-./:;&lt;=&gt;?@[\]^_`{|}~)</code>.
</p>
<p>
For best practices of using <code>MessageGroupId</code>, see <a href=
"https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/using-messagegroupid-property.html"
>Using the MessageGroupId Property</a> in the <i>Amazon SQS Developer Guide</i>.
</p>
<important>
<p>
<code>MessageGroupId</code> is required for FIFO queues. You can't use it for Standard queues.
</p>
</important>

@return This parameter applies only to FIFO (first-in-first-out) queues.</p>
        <p>
        The tag that specifies that a message belongs to a specific message group. Messages that belong to the
        same message group are processed in a FIFO manner (however, messages in different message groups might be
        processed out of order). To interleave multiple ordered streams within a single queue, use
        <code>MessageGroupId</code> values (for example, session data for multiple users). In this scenario,
        multiple consumers can process the queue, but the session data of each user is processed in a FIFO
        fashion.
        </p>
        <ul>
        <li>
        <p>
        You must associate a non-empty <code>MessageGroupId</code> with a message. If you don't provide a
        <code>MessageGroupId</code>, the action fails.
        </p>
        </li>
        <li>
        <p>
        <code>ReceiveMessage</code> might return messages with multiple <code>MessageGroupId</code> values. For
        each <code>MessageGroupId</code>, the messages are sorted by time sent. The caller can't specify a
        <code>MessageGroupId</code>.
        </p>
        </li>
        </ul>
        <p>
        The maximum length of <code>MessageGroupId</code> is 128 characters. Valid values: alphanumeric
        characters and punctuation <code>(!"#$%&amp;'()*+,-./:;&lt;=&gt;?@[\]^_`{|}~)</code>.
        </p>
        <p>
        For best practices of using <code>MessageGroupId</code>, see <a href=
        "https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/using-messagegroupid-property.html"
        >Using the MessageGroupId Property</a> in the <i>Amazon SQS Developer Guide</i>.
        </p>
        <important>
        <p>
        <code>MessageGroupId</code> is required for FIFO queues. You can't use it for Standard queues.
        </p>
aws-java-sdk-sqs/src/main/java/com/amazonaws/services/sqs/model/SendMessageRequest.java