public String getMessageDeduplicationId() {
        return this.messageDeduplicationId;
    }
<p>
This parameter applies only to FIFO (first-in-first-out) topics.
</p>
<p>
The token used for deduplication of messages within a 5-minute minimum deduplication interval. If a message with
a particular <code>MessageDeduplicationId</code> is sent successfully, subsequent messages with the same
<code>MessageDeduplicationId</code> are accepted successfully but aren't delivered.
</p>
<ul>
<li>
<p>
Every message must have a unique <code>MessageDeduplicationId</code>.
</p>
<ul>
<li>
<p>
You may provide a <code>MessageDeduplicationId</code> explicitly.
</p>
</li>
<li>
<p>
If you aren't able to provide a <code>MessageDeduplicationId</code> and you enable
<code>ContentBasedDeduplication</code> for your topic, Amazon SNS uses a SHA-256 hash to generate the
<code>MessageDeduplicationId</code> using the body of the message (but not the attributes of the message).
</p>
</li>
<li>
<p>
If you don't provide a <code>MessageDeduplicationId</code> and the topic doesn't have
<code>ContentBasedDeduplication</code> set, the action fails with an error.
</p>
</li>
<li>
<p>
If the topic has a <code>ContentBasedDeduplication</code> set, your <code>MessageDeduplicationId</code> overrides
the generated one.
</p>
</li>
</ul>
</li>
<li>
<p>
When <code>ContentBasedDeduplication</code> is in effect, messages with identical content sent within the
deduplication interval are treated as duplicates and only one copy of the message is delivered.
</p>
</li>
<li>
<p>
If you send one message with <code>ContentBasedDeduplication</code> enabled, and then another message with a
<code>MessageDeduplicationId</code> that is the same as the one generated for the first
<code>MessageDeduplicationId</code>, the two messages are treated as duplicates and only one copy of the message
is delivered.
</p>
</li>
</ul>
<note>
<p>
The <code>MessageDeduplicationId</code> is available to the consumer of the message (this can be useful for
troubleshooting delivery issues).
</p>
<p>
If a message is sent successfully but the acknowledgement is lost and the message is resent with the same
<code>MessageDeduplicationId</code> after the deduplication interval, Amazon SNS can't detect duplicate messages.
</p>
<p>
Amazon SNS continues to keep track of the message deduplication ID even after the message is received and
deleted.
</p>
</note>
<p>
The length of <code>MessageDeduplicationId</code> is 128 characters.
</p>
<p>
<code>MessageDeduplicationId</code> can contain alphanumeric characters <code>(a-z, A-Z, 0-9)</code> and
punctuation <code>(!"#$%&amp;'()*+,-./:;&lt;=&gt;?@[\]^_`{|}~)</code>.
</p>

@return This parameter applies only to FIFO (first-in-first-out) topics.</p>
        <p>
        The token used for deduplication of messages within a 5-minute minimum deduplication interval. If a
        message with a particular <code>MessageDeduplicationId</code> is sent successfully, subsequent messages
        with the same <code>MessageDeduplicationId</code> are accepted successfully but aren't delivered.
        </p>
        <ul>
        <li>
        <p>
        Every message must have a unique <code>MessageDeduplicationId</code>.
        </p>
        <ul>
        <li>
        <p>
        You may provide a <code>MessageDeduplicationId</code> explicitly.
        </p>
        </li>
        <li>
        <p>
        If you aren't able to provide a <code>MessageDeduplicationId</code> and you enable
        <code>ContentBasedDeduplication</code> for your topic, Amazon SNS uses a SHA-256 hash to generate the
        <code>MessageDeduplicationId</code> using the body of the message (but not the attributes of the
        message).
        </p>
        </li>
        <li>
        <p>
        If you don't provide a <code>MessageDeduplicationId</code> and the topic doesn't have
        <code>ContentBasedDeduplication</code> set, the action fails with an error.
        </p>
        </li>
        <li>
        <p>
        If the topic has a <code>ContentBasedDeduplication</code> set, your <code>MessageDeduplicationId</code>
        overrides the generated one.
        </p>
        </li>
        </ul>
        </li>
        <li>
        <p>
        When <code>ContentBasedDeduplication</code> is in effect, messages with identical content sent within the
        deduplication interval are treated as duplicates and only one copy of the message is delivered.
        </p>
        </li>
        <li>
        <p>
        If you send one message with <code>ContentBasedDeduplication</code> enabled, and then another message
        with a <code>MessageDeduplicationId</code> that is the same as the one generated for the first
        <code>MessageDeduplicationId</code>, the two messages are treated as duplicates and only one copy of the
        message is delivered.
        </p>
        </li>
        </ul>
        <note>
        <p>
        The <code>MessageDeduplicationId</code> is available to the consumer of the message (this can be useful
        for troubleshooting delivery issues).
        </p>
        <p>
        If a message is sent successfully but the acknowledgement is lost and the message is resent with the same
        <code>MessageDeduplicationId</code> after the deduplication interval, Amazon SNS can't detect duplicate
        messages.
        </p>
        <p>
        Amazon SNS continues to keep track of the message deduplication ID even after the message is received and
        deleted.
        </p>
        </note>
        <p>
        The length of <code>MessageDeduplicationId</code> is 128 characters.
        </p>
        <p>
        <code>MessageDeduplicationId</code> can contain alphanumeric characters <code>(a-z, A-Z, 0-9)</code> and
        punctuation <code>(!"#$%&amp;'()*+,-./:;&lt;=&gt;?@[\]^_`{|}~)</code>.
aws-java-sdk-sns/src/main/java/com/amazonaws/services/sns/model/PublishBatchRequestEntry.java