public PostTextRequest withUserId(String userId) {
        setUserId(userId);
        return this;
    }
<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>

@param userId
       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>
@return Returns a reference to this object so that method calls can be chained together.
aws-java-sdk-lex/src/main/java/com/amazonaws/services/lexruntime/model/PostTextRequest.java