Smack currently does unnecessary escaping of XML text, where it
escapes e.g. '"' to '"'. This bloats the stanza size, especially
if JSON payloads are involved.
Fixes SMACK-892 (although there are probably still places where
XmlStringBuilder.escape() is used when XmlStringBuild.text() could
have been used).
Returning a generic would allow for
List<ExtensionElement> list = stanza.getExtension("foo", "bar");
to compile (Note the we are calling getExtension(), not
getExtension*s*()).
Users are encouraged to use the type safe getExtension(Class<? extends
ExtensionElement) variant instead.
Fixes SMACK-825.