ExtensionElement is now a marker interface that requires all
implementation non-abstract classes to carry a static final QNAME
field (of type QName). This is verified by a new unit test.
Also FullyQualifiedElement is renamed to simply XmlElement. XmlElement
is used over ExtensionElement when implementing classes do not
statically know the qualified name of the XML elements they
represent. In general, XmlElement should be used sparingly, and every
XML element should be modeled by its own Java class (implementing
ExtensionElement).
This also resulted in a refactoring of the Providers and parsing
Exceptions. NumberFormatException and ParseException can now be thrown
directly, the wrapping in a SmackParsingException is down at a higher
layer, i.e. in AbstractProvider.
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).
This moves the logic in AbstractXMPPConnection.getSmackTlsContext()
into the ConnectionConfiguration constructor.
Also introduce SslContextFactory and use it in
ConnectionConfiguration.
Apply builder pattern to form fields and replace getVariable() with
getFieldName(). Refer to the field name as "field name" instead of
"variable" everyone, just as XEP-0004 does.
Improve the high-level form API: introduce FilledForm and FillableForm
which perform stronger validation and consistency checks.
Also add FormFieldRegistry to enable processing of 'submit' forms
where the form field types are omitted.
Smack also now does omit the form field type declaration on 'submit'
type forms, as it is allowed by XEP-0004.
If it is announced as feature, entities sending fastened messages
expect the recipient to react somehow on those. And this is not the
case if this is just enabled in Smack.
Hence we disable it per default and require smack users to explicitly
enable it after they have setup the according stanza listeners.
This also removes the powermock dependency. Although powermock is a
fine library, it currently prevents dropping Junit4. And since we only
use the Whitebox API of powermock, this simply replaced powermock's
Whitebox with our own.
