Stop regenerating openapitools.json in multiple folders

cmake/dbGenCpp.cmake

@@ -1,7 +1,6 @@
 include_guard(GLOBAL)
 
 include("${CMAKE_CURRENT_LIST_DIR}/dbGenerationCommon.cmake")
-set(_CPPBESSOT_DB_GEN_CPP_DIR "${CMAKE_CURRENT_LIST_DIR}")
 
 function(cppbessot_add_db_gen_cpp_target schema_dir)
   # Purpose: Register C++ model generation target using checked-in templates.
@@ -13,11 +12,7 @@ function(cppbessot_add_db_gen_cpp_target schema_dir)
   #   - Files under `<schema_dir>/generated-cpp-source`.
   cppbessot_validate_schema_dir_name("${schema_dir}")
   cppbessot_get_schema_dir_path(_version_dir "${schema_dir}")
-  if(DEFINED CPPBESSOT_MODULE_ROOT AND NOT "${CPPBESSOT_MODULE_ROOT}" STREQUAL "")
-    set(_module_root "${CPPBESSOT_MODULE_ROOT}")
-  else()
-    get_filename_component(_module_root "${_CPPBESSOT_DB_GEN_CPP_DIR}/.." ABSOLUTE)
-  endif()
+  cppbessot_get_module_root(_module_root)
 
   set(_openapi_file "${_version_dir}/openapi/openapi.yaml")
   set(_template_dir "${_module_root}/openapi/templates/cpp-odb-json")
@@ -40,6 +35,7 @@ function(cppbessot_add_db_gen_cpp_target schema_dir)
             -o "${_output_dir}"
             --global-property models
     DEPENDS "${_openapi_file}" ${_template_inputs}
+    WORKING_DIRECTORY "${_module_root}"
     COMMENT "Generating C++ model headers/sources for ${schema_dir}"
     VERBATIM
   )