@Nullable
    TypeConversionDescriptor findCompoundAssignmentConversion(@NotNull PsiType from,
                                                              @NotNull PsiExpression expression,
                                                              @NotNull String sign,
                                                              @NotNull String binarySign) {
      return null;
    }
@Nullable
    TypeConversionDescriptor findCompoundAssignmentConversion(@NotNull PsiType from,
                                                              @NotNull PsiExpression expression,
                                                              @NotNull String sign,
                                                              @NotNull String binarySign)