public GCMMessage withPreferredAuthenticationMethod(String preferredAuthenticationMethod) {
        setPreferredAuthenticationMethod(preferredAuthenticationMethod);
        return this;
    }
<p>
The preferred authentication method, with valid values "KEY" or "TOKEN". If a value isn't provided then the
<b>DefaultAuthenticationMethod</b> is used.
</p>

@param preferredAuthenticationMethod
       The preferred authentication method, with valid values "KEY" or "TOKEN". If a value isn't provided then
       the <b>DefaultAuthenticationMethod</b> is used.
@return Returns a reference to this object so that method calls can be chained together.
aws-java-sdk-pinpoint/src/main/java/com/amazonaws/services/pinpoint/model/GCMMessage.java