“threadsafe” modifier in JAVA?

Question

I just came across a BNF Grammar for JAVA. In it, "modifier" has a terminal symbol called "threadsafe". However, I have never seen it before and have not been able to locate that modifier in The Java Language Specification, Java SE 7 Edition (docs.oracle.com/javase/specs/jls/se7/jls7.pdf). Yet, I found it here, describing it in bullet 16 as:

If another thread excuting this code at the same time can not change the value of a variable then the variable is threadsafe and the compiler may do clever things with it to make the code faster or smaller.

Is this a real modifier? Is it supposed to be introduced in upcomming versions of JAVA?

Answer 1

Try to find it here, at the official source of Java BNF.

Answer 2

No it's not, nor is private_protected in the same list.

Answer 3

Both Java and Groovy have keywords like "threadsafe" and "goto" as "reserved tokens" in the compiler, but they have no meaning right now in the language.