Meson CMake subproject with "default_library=static"

[DevLewa]

Apologies in advance if this was already answered. (I wasn't able to find anything regarding this specific issue.)

I'm currently attempting to build a console based exe and link against a cmake based subproject (the assimp library) but doing so with static linking. (By default a shared lib is built and linked against.)
The assimp source code is placed in the subprojects directory of the project.

Meson seems to support per-subproject settings (https://mesonbuild.com/Subprojects.html) that can achieve this with "default options".

libsimple_dep = dependency(
  'libsimple',
  fallback : ['libsimple', 'libsimple_dep'],
  default_options: ['default_library=static']
)

I tried:

cmake = import('cmake')
assimp_proj = cmake.subproject('assimp-5.4.1', default_options: ['default_library=static'])
assimp_lib = assimp_proj.dependency('assimp')

and

cmake = import('cmake')
assimp_proj = cmake.subproject('assimp-5.4.1')
assimp_lib = assimp_proj.dependency('assimp', default_options: ['default_library=static'])

But in both cases "default_options" is not recognized:
ERROR: cmake.subproject got unknown keyword arguments "default_options"

Am i applying this incorrectly? Any hints/directions would be greatly appreciated.