StringSubstitutions are disabled in 1.9

[Dmitry Samersoff]

Hi Everybody,

1.
I found following remark in StringSubstitutionTest.java

if (!Java8OrEarlier) {
   // StringSubstitutions are disabled in 1.9
    return;
}


What is the reason for disabling StringSubstitutions in jdk9 and should
we enable it for jdk11?

2.
StringSubstitutionTest.testSubstitution method is almost identical to
one in its baseclass, MethodSubstitutionTest.testSubstitution.

What is the reason of that slight diverge?

Should we create more specific StringSubstitutionTest class?

Regards,
-Dmitry