static CallHandler<CallChainSimplification> handler() {
      return CallHandler.of(STREAM_COLLECT, call -> {
        if (extractDelimiter(call) == null) return null;
        PsiMethodCallExpression qualifier = getQualifierMethodCall(call);
        if (qualifier == null) return null;
        if (ARRAYS_STREAM.matches(qualifier) ||
            (COLLECTION_STREAM.matches(qualifier) && ExpressionUtils.getEffectiveQualifier(qualifier.getMethodExpression()) != null)) {
          PsiType elementType = StreamApiUtil.getStreamElementType(qualifier.getType());
          if (InheritanceUtil.isInheritor(elementType, JAVA_LANG_CHAR_SEQUENCE)) {
            return new JoiningStringsFix();
          }
        }
        return null;
      });
    }
static CallHandler<CallChainSimplification> handler()