join collection to string , separator is #default_join_separator join null = '' '' ; join = '' '' ; join a , b = `` a , b '' ; concode_field_sep CharSequence DEFAULT_JOIN_SEPARATOR concode_field_sep boolean isEmpty
String function ( Iterable arg0 ) { return arg0 == null ? "srini_string" : TextUtils . join ( DEFAULT_JOIN_SEPARATOR , arg0 ) ; }