code: public ConstructorDoc[] constructors(boolean filter) {
          Names names = tsym.name.table.names;
          List<ConstructorDocImpl> constructors = List.nil();
          for (Symbol sym : tsym.members().getSymbols(NON_RECURSIVE)) {
              if (sym != null &&
                  sym.kind == MTH && sym.name == names.init) {
                  MethodSymbol s = (MethodSymbol)sym;
                  if (!filter || env.shouldDocument(s)) {
                      constructors = constructors.prepend(env.getConstructorDoc(s));
                  }
              }
          }
          //### Cache constructors here?
          return constructors.toArray(new ConstructorDocImpl[constructors.length()]);
      }
docs: Return constructors in class.
  
  @param filter include only the included constructors if filter==true
  @return an array of ConstructorDocImpl for representing the visible
  constructors in this class.