Quoth JLS #8.1.3:
Inner classes may not declare static initializers (§8.7)......
This is demonstrated as such:<
There's a contradiction by definition:
From JLS §8.1.3:
A statement or expression occurs in a static context if and only if the innermost method, constructor, instance initializer, static initializer, field initializer, or explicit constructor invocation statement enclosing the statement or expression is a static method, a static initializer, the variable initializer of a static variable, or an explicit constructor invocation statement (§8.8.7).
...
When an inner class (whose declaration does not occur in a static context) refers to an instance variable that is a member of a lexically enclosing class, the variable of the corresponding lexically enclosing instance is used.