Bind an inputRichText to a Bean

I'm trying to bind an xp:inputRichText to a bean (ChatBean), but get this validation error when the code tries update the field to the bean:

java.lang.IllegalArgumentException: argument type mismatch

I've tried a few of different things like converters to make sure the text will be a string, printing debug messages to find out where things go wrong, changed the type of the "setChatContent()" method (that sets the input to read-only), but can't get it to work.

Am I missing something, or is it not possible? Any thoughts?

The page:

<?xml version="1.0" encoding="UTF-8"?>
<xp:view xmlns:xp="http://www.ibm.com/xsp/core">
<xp:messages id="messages1"></xp:messages>

<xp:inputRichText id="inputRichText1" value="#{Chat.chatContent}"></xp:inputRichText>

<xp:button value="Save" id="button1" type="button">
    <xp:eventHandler event="onclick" submit="true" refreshMode="complete" save="false">
        <xp:this.action>
            <xp:actionGroup>
                <xp:executeScript script="#{javascript:Chat.saveContent();}"></xp:executeScript>
                <xp:openPage name="/chat.xsp"></xp:openPage>
            </xp:actionGroup>
        </xp:this.action>
    </xp:eventHandler>
</xp:button>

The error occurs after I hit the "Save" button, which calls a method on the Chat bean (code is shortened):

public class ChatBean implements Serializable {
    private static final long serialVersionUID = 1L;
    private String chatContent;

    public String getChatContent() {
        return chatContent;
    }

    public void setChatContent(String chatContent) {
        this.chatContent = chatContent;
    }

    public void saveContent() {
        // TODO implement save
        this.chatContent = "";
    }
}

The UIInputRichText requires an object of type com.ibm.xsp.http.MimeMultipart

If you change your ChatBean to work with this instead, it should work as desired:

public class ChatBean implements Serializable {
   private static final long serialVersionUID = 1L;
   private com.ibm.xsp.http.MimeMultipart chatContent;

   public com.ibm.xsp.http.MimeMultipart getChatContent() {
       return chatContent;
   }

   public void setChatContent(com.ibm.xsp.http.MimeMultipart chatContent) {
       this.chatContent = chatContent;
   }

   public void saveContent() {
       // TODO implement save
       this.chatContent = null;
   }
}