NDK project build with multiple CMakeFiles.txt - gradle

Question

My intent is to have prebuilt libprebuilt.so and libmylib.so built into the apk. My project is structured like this
|-mylib_prebuilts
| |-libprebuilt.so
| |-include_dir
| '-CMakeFiles.txt
|-mylib
| |-src
| '-CMakeFiles.txt
'-build.gradle
In the CMakeFiles.txt for mylib_prebuilts, I have the following.
add_library(prebuiltlib SHARED IMPORTED)
target_include_directories(prebuiltlib INTERFACE include_dir)
set_property(TARGET prebuiltlib PROPERTY IMPORTED_LOCATION libprebuilt.so)
In the CMakeFiles.txt for lib, I have the following
add_subdirectory(../mylib_prebuilts mylib_prebuilts)
add_library(mylib SHARED ${srcs})
target_link_libraries(mylib PUBLIC prebuiltlib)
The root gradle.build has the following
externalNativeBuild {
cmake {
version '3.18.1'
path 'mylib/CMakeLists.txt'
}
}
I cannot reach the prebuilt headers or library from mylib. I get "headers not found" error, or if I manually add the header path using include_directories(../mylib_prebuilts/include_dir), build cannot find symbols when linking.

Answer 1

Answering my own question with a solution I stumbled upon.
mylib_prebuilts/CMakeLists.txt has to contain the following changes.
Add GLOBAL keyword to add_library call.
Use absolute path instead
of relative for set_property call using ${MAKE_CURRENT_SOURCE_DIR}
variable
add_library(prebuiltlib SHARED IMPORTED GLOBAL)
target_include_directories(prebuiltlib INTERFACE include_dir)
set_property(TARGET prebuiltlib PROPERTY IMPORTED_LOCATION ${MAKE_CURRENT_SOURCE_DIR}/libprebuilt.so)