private static boolean usagesAreAllowed(@NotNull PsiVariable firstParam,
                                            @NotNull PsiVariable secondParam,
                                            @Nullable PsiExpression firstExpr,
                                            @Nullable PsiExpression secondExpr) {
      return VariableAccessUtils.variableIsUsed(firstParam, firstExpr) &&
             VariableAccessUtils.variableIsUsed(secondParam, secondExpr) &&
             !VariableAccessUtils.variableIsUsed(firstParam, secondExpr) &&
             !VariableAccessUtils.variableIsUsed(secondParam, firstExpr);
    }
private static boolean usagesAreAllowed(@NotNull PsiVariable firstParam,
                                            @NotNull PsiVariable secondParam,
                                            @Nullable PsiExpression firstExpr,
                                            @Nullable PsiExpression secondExpr)