XmlUtil.findSubTag and PHPStorm 5

Hi! I'm getting an error on this method in PHPStorm 5

java.lang.NoSuchMethodError: com.intellij.xml.util.XmlUtil.findSubTag(Lcom/intellij/psi/xml/XmlTag;Ljava/lang/String;)Lcom/intellij/psi/xml/XmlTag;

it looks like the method doesn't exist in XmlUtil anymore.

Can you tell me if there's some replacemente for that method? and in that case, how should I manage that from my plugin so it works in PHPStorm 4 too ?

Thanks !