For testcase
=============

jtools-sqe:/home/vr128054/vertest/work/javah 2296 % more m.java
class test
{
        public void doNothing ()
        {
                interface testable
                {
                }

                class local
                {
                }
        }
}


The error message is
=====================

jtools-sqe:/home/vr128054/vertest/work/javah 2300 % javac m.java
m.java:5: modifier interface not allowed here
                interface testable
                ^
1 error

To call an 'interface' keyword a modifier looks odd.