A DESCRIPTION OF THE REQUEST :
com.sun.source.tree.ClassTree claims to represent "A tree node for a class, interface, enum, or annotation type declaration" yet it does not expose a way to detect whether its type is a interface, enum or annotation type (that is, the type is always a "class").

ClassTree.getModifiers() returns ModifiersTree which in turn has a method getFlags() but this method will never return an interface, enum or annotation type.

The source code for Modifier.java contains this comment:

// java.lang.reflect.Modifier includes INTERFACE, but that's a VMism.

so it looks as if this omission was by design. If you investigate further you will find that Pretty.java (used to pretty-print Trees) uses internal methods to detect the class type but there doesn't seem to be a way to do the same using public methods.

Please clarify how to detect a class, inteface, enum or annotation type using the Tree API using the public methods.

JUSTIFICATION :
The Tree API is incomplete without the ability to detect the class type.