public void setMasterUsername(String masterUsername) {
        this.masterUsername = masterUsername;
    }
<p>
The name for the master user.
</p>
<p>
<b>MySQL</b>
</p>
<p>
Constraints:
</p>
<ul>
<li>
<p>
Required for MySQL.
</p>
</li>
<li>
<p>
Must be 1 to 16 letters or numbers. Can contain underscores.
</p>
</li>
<li>
<p>
First character must be a letter.
</p>
</li>
<li>
<p>
Can't be a reserved word for the chosen database engine.
</p>
<p>
For more information about reserved words in MySQL 5.6 or 5.7, see the Keywords and Reserved Words articles for
<a href="https://dev.mysql.com/doc/refman/5.6/en/keywords.html">MySQL 5.6</a>, <a
href="https://dev.mysql.com/doc/refman/5.7/en/keywords.html">MySQL 5.7</a>, or <a
href="https://dev.mysql.com/doc/refman/8.0/en/keywords.html">MySQL 8.0</a>.
</p>
</li>
</ul>
<p>
<b>PostgreSQL</b>
</p>
<p>
Constraints:
</p>
<ul>
<li>
<p>
Required for PostgreSQL.
</p>
</li>
<li>
<p>
Must be 1 to 63 letters or numbers. Can contain underscores.
</p>
</li>
<li>
<p>
First character must be a letter.
</p>
</li>
<li>
<p>
Can't be a reserved word for the chosen database engine.
</p>
<p>
For more information about reserved words in MySQL 5.6 or 5.7, see the Keywords and Reserved Words articles for
<a href="https://www.postgresql.org/docs/9.6/sql-keywords-appendix.html">PostgreSQL 9.6</a>, <a
href="https://www.postgresql.org/docs/10/sql-keywords-appendix.html">PostgreSQL 10</a>, <a
href="https://www.postgresql.org/docs/11/sql-keywords-appendix.html">PostgreSQL 11</a>, and <a
href="https://www.postgresql.org/docs/12/sql-keywords-appendix.html">PostgreSQL 12</a>.
</p>
</li>
</ul>

@param masterUsername
       The name for the master user.</p>
       <p>
       <b>MySQL</b>
       </p>
       <p>
       Constraints:
       </p>
       <ul>
       <li>
       <p>
       Required for MySQL.
       </p>
       </li>
       <li>
       <p>
       Must be 1 to 16 letters or numbers. Can contain underscores.
       </p>
       </li>
       <li>
       <p>
       First character must be a letter.
       </p>
       </li>
       <li>
       <p>
       Can't be a reserved word for the chosen database engine.
       </p>
       <p>
       For more information about reserved words in MySQL 5.6 or 5.7, see the Keywords and Reserved Words
       articles for <a href="https://dev.mysql.com/doc/refman/5.6/en/keywords.html">MySQL 5.6</a>, <a
       href="https://dev.mysql.com/doc/refman/5.7/en/keywords.html">MySQL 5.7</a>, or <a
       href="https://dev.mysql.com/doc/refman/8.0/en/keywords.html">MySQL 8.0</a>.
       </p>
       </li>
       </ul>
       <p>
       <b>PostgreSQL</b>
       </p>
       <p>
       Constraints:
       </p>
       <ul>
       <li>
       <p>
       Required for PostgreSQL.
       </p>
       </li>
       <li>
       <p>
       Must be 1 to 63 letters or numbers. Can contain underscores.
       </p>
       </li>
       <li>
       <p>
       First character must be a letter.
       </p>
       </li>
       <li>
       <p>
       Can't be a reserved word for the chosen database engine.
       </p>
       <p>
       For more information about reserved words in MySQL 5.6 or 5.7, see the Keywords and Reserved Words
       articles for <a href="https://www.postgresql.org/docs/9.6/sql-keywords-appendix.html">PostgreSQL 9.6</a>,
       <a href="https://www.postgresql.org/docs/10/sql-keywords-appendix.html">PostgreSQL 10</a>, <a
       href="https://www.postgresql.org/docs/11/sql-keywords-appendix.html">PostgreSQL 11</a>, and <a
       href="https://www.postgresql.org/docs/12/sql-keywords-appendix.html">PostgreSQL 12</a>.
       </p>
       </li>
aws-java-sdk-lightsail/src/main/java/com/amazonaws/services/lightsail/model/CreateRelationalDatabaseRequest.java