[WP77xx] STRING definition that compiler understands

Hello,

WP7702 & Legato 18.06.1 & poky-swi-ext-glibc-x86_64-meta-toolchain-swi-ext-armv7a-neon-toolchain-swi-ext-2.2.3.sh

I want to set a flag (in my .cdef file) like:

cxxflags:
{
-DMY_STRING="This is my string"
}

Unfortunally when I do that I see in compiler arg line the line bellow and compiling fails:
-DMY_STRING= "This is my string"

As you can see there is one extra space after ‘=’ sign. I am unsure if that is the problem
I tried various ways to do this using /" or " or \ or \" and none of these work.
How can I set a string define trough .cdef file?

Other defines work, only the string define is making problems, I guess its some bug in the .CDEF parser or something like that?

EDIT:
When I try
-DMY_STRING=This is my string
compiling also fails because in my code I have something like this:
str.append(“This is my string value” + string(MY_STRING));

It fails because its missing quotations signs.