Review

HashMap.get() throws if the key is null. Since you don't know which implementation of Map you get, you should always guard against this.

Check that the key is not null before calling Map.get().

• missing/condition/null_check

MapKeyNull.java

misuse(HashMap, String)

class MapKeyNull {
	Object misuse(HashMap<String, Object> m, String key) {
		return m.get(key);
	}

}