What do square brackets in Java method declarations mean?

Question

The grammar for method declarations in Java is something like the following:

Java method declaration BNF:

method_declaration 
    ::= 
    { modifier         


        

Answer 1

{ ... } stands for 0..* (zero times or more)

The generics are missing because the document you linked is 17 years old.

The official Java Language Specification uses this particular syntax: http://docs.oracle.com/javase/specs/jls/se7/html/jls-2.html#jls-2.4

I wasn't able to find a real BNF grammar for Java which is less obsolete than yours.