Cap'n Proto CMake support: CAPNP_LIB_CAPNP-JSON is NOTFOUND - c++

Question

Why do I have to set
set(CAPNP_LIB_CAPNP-JSON "")
in my CMakeLists.txt in order to not get an error? Error as follows:
CMake Error: The following variables are used in this project, but they are set to NOTFOUND.
Please set them or make sure they are set and tested correctly in the CMake files:
CAPNP_LIB_CAPNP-JSON (ADVANCED)
linked by target "client" in directory <...>
linked by target "server" in directory <...>
The way I'm using capnproto CMake support is by copying the cmake file included in the capnproto source into my project and including it manually. (Is there a better / standard way to do this? Feels hackish.) The rest is just taken from the CMake file's instructions.
CMake snippet:
# so capnp cmake plugin is found
set(CapnProto_DIR "${CMAKE_CURRENT_SOURCE_DIR}/etc/cmake")
# for some reason there is some json lib or something that isn't found?
#set(CAPNP_LIB_CAPNP-JSON "")
find_package(CapnProto REQUIRED)
include_directories(${CAPNP_INCLUDE_DIRS})
add_definitions(${CAPNP_DEFINITIONS})
set(CAPNPC_SRC_PREFIX "src/capnp")
# capnp out of source config
set(CAPNPC_OUTPUT_DIR ${CMAKE_CURRENT_BINARY_DIR})
include_directories(${CAPNPC_OUTPUT_DIR})
# gen cpp
capnp_generate_cpp(CAPNP_SRCS CAPNP_HDRS
src/capnp/schema.capnp
)
CMake 3.6.2, building using CLion's integrated build commands. capnp is installed via homebrew, latest version.
Why am I getting the error about the JSON bit? What is that about?
Also, is there a better way for including the official Cap'n Proto CMake file? It seemed to not get distributed with the header and library files when installing via homebrew.

Answer 1

It turns out json encoding/decoding support is an as yet (Oct 2016) unreleased feature of Cap'n Proto and trying to use the .cmake file from the master branch with the last released version produces this conflict.
Possible solutions:
1) Use workaround posted in the question, i.e.
set(CAPNP_LIB_CAPNP-JSON "") # add this before next line
find_package(CapnProto REQUIRED)
2) Use the released version of the .cmake script here: FindCapnProto.cmake
3) Build and install Cap'n Proto from source, use with latest .cmake script.