public void setPattern(String pattern) {
        this.pattern = pattern;
    }
<p>
A regular expression used to validate the value of a slot.
</p>
<p>
Use a standard regular expression. Amazon Lex supports the following characters in the regular expression:
</p>
<ul>
<li>
<p>
A-Z, a-z
</p>
</li>
<li>
<p>
0-9
</p>
</li>
<li>
<p>
Unicode characters ("\ u&lt;Unicode&gt;")
</p>
</li>
</ul>
<p>
Represent Unicode characters with four digits, for example "\u0041" or "\u005A".
</p>
<p>
The following regular expression operators are not supported:
</p>
<ul>
<li>
<p>
Infinite repeaters: *, +, or {x,} with no upper bound.
</p>
</li>
<li>
<p>
Wild card (.)
</p>
</li>
</ul>

@param pattern
       A regular expression used to validate the value of a slot. </p>
       <p>
       Use a standard regular expression. Amazon Lex supports the following characters in the regular expression:
       </p>
       <ul>
       <li>
       <p>
       A-Z, a-z
       </p>
       </li>
       <li>
       <p>
       0-9
       </p>
       </li>
       <li>
       <p>
       Unicode characters ("\ u&lt;Unicode&gt;")
       </p>
       </li>
       </ul>
       <p>
       Represent Unicode characters with four digits, for example "\u0041" or "\u005A".
       </p>
       <p>
       The following regular expression operators are not supported:
       </p>
       <ul>
       <li>
       <p>
       Infinite repeaters: *, +, or {x,} with no upper bound.
       </p>
       </li>
       <li>
       <p>
       Wild card (.)
       </p>
       </li>
aws-java-sdk-lexmodelbuilding/src/main/java/com/amazonaws/services/lexmodelbuilding/model/SlotTypeRegexConfiguration.java