There is two template in my .stg file, and both of them apply on multi-value a HashMap. The HashMap is employed as an injected object. And I need those instance of HashMap can be injected for many times. My trouble is, when I switch to another template, ANTLR seems to consider the second HashMap as a List -- multipul objects and null value. Part of my .stg file shows as follows: tpl_hash(BAR, FOO) ::= << <FOO:foo(); separator="\n"> <BAR:bar(); separator="\n"> >> foo(nn) ::= << foo: <nn.name; null="NULL"> . <nn.national; null="NULL"> >> bar(mm) ::= << bar: <mm.name> @ <mm.national> >> Part of my .g file shows: HashMap hm = new HashMap(); hm.put("name", $name.text); hm.put("national", "German"); tpl_hash.add("FOO",new HashMap(hm)); HashMap hm2 = new HashMap(); hm2.put("name", $name.text); hm2.put("national", "German"); tpl_hash.add("BAR",new HashMap(hm2)); The result I expect is : bar: Kant @ German foo: Russell @ England But, I got: foo: NULL . NULL foo: NULL . NULL bar: @ bar: @ If we replace BAR with FOO, as is, keeping FOO and BAR with identical template, the output is right, like the following. bar: Russell @ German bar: Russell @ German In docs, "synchronized ST add (String name, Object value) in org.stringtemplate.v4.ST" said: "If you send in a List and then inject a single value element, add() copies original list and adds the new value." What about a HashMap? Does ANTLR consider the HashMap, key/value pair access, an object purposely, as a List and as multi-value injected by mistake? Thanks a lot in advance.