Syntax Registry

There's now the concept of a Syntax Registry and new Syntaxes are expected to register themselves in that registry. 

You can list all registered syntaxes using:

@Inject
private SyntaxRegistry registry;
...
List<Syntax> syntaxes = registry.getSyntaxes();

You can also get a Syntax object from a Syntax id string using (for example):

@Inject
private SyntaxRegistry registry;
...
Optional<Syntax> syntax = registry.getSyntax("xwiki/2.1");

See available Syntaxes for more.