According to specification:

j.l.i.MethodHandles.whileLoop(MH, MH, MH)
body - body of the loop, which may not be null.
j.l.i.MethodHandles.doWhileLoop(MH, MH, MH)
body - body of the loop, which may not be null.

Actually, both methods permit body=null, moreover code from 'implementation notes' sections permits body=null too (no IllegalArgumentException).

Was found on jdk9b107, tests are under development, tck_red will be added after development completion.

Example is attached