public String getUserId() {
        return this.userId;
    }
<p>
The ID of the client application user. Amazon Lex uses this to identify a user's conversation with your bot. At
runtime, each request must contain the <code>userID</code> field.
</p>
<p>
To decide the user ID to use for your application, consider the following factors.
</p>
<ul>
<li>
<p>
The <code>userID</code> field must not contain any personally identifiable information of the user, for example,
name, personal identification numbers, or other end user personal information.
</p>
</li>
<li>
<p>
If you want a user to start a conversation on one device and continue on another device, use a user-specific
identifier.
</p>
</li>
<li>
<p>
If you want the same user to be able to have two independent conversations on two different devices, choose a
device-specific identifier.
</p>
</li>
<li>
<p>
A user can't have two independent conversations with two different versions of the same bot. For example, a user
can't have a conversation with the PROD and BETA versions of the same bot. If you anticipate that a user will
need to have conversation with two different versions, for example, while testing, include the bot alias in the
user ID to separate the two conversations.
</p>
</li>
</ul>

@return The ID of the client application user. Amazon Lex uses this to identify a user's conversation with your
        bot. At runtime, each request must contain the <code>userID</code> field.</p>
        <p>
        To decide the user ID to use for your application, consider the following factors.
        </p>
        <ul>
        <li>
        <p>
        The <code>userID</code> field must not contain any personally identifiable information of the user, for
        example, name, personal identification numbers, or other end user personal information.
        </p>
        </li>
        <li>
        <p>
        If you want a user to start a conversation on one device and continue on another device, use a
        user-specific identifier.
        </p>
        </li>
        <li>
        <p>
        If you want the same user to be able to have two independent conversations on two different devices,
        choose a device-specific identifier.
        </p>
        </li>
        <li>
        <p>
        A user can't have two independent conversations with two different versions of the same bot. For example,
        a user can't have a conversation with the PROD and BETA versions of the same bot. If you anticipate that
        a user will need to have conversation with two different versions, for example, while testing, include
        the bot alias in the user ID to separate the two conversations.
        </p>
        </li>
aws-java-sdk-lex/src/main/java/com/amazonaws/services/lexruntime/model/PostTextRequest.java