#550 Remove redundant warning about Doxygen

Signed-off-by: Martin Stump <11492152+globberwops@users.noreply.github.com>

Author: globberwops

CMakeLists.txt

@@ -244,14 +244,9 @@ install(EXPORT ${PROJECT_NAME}_targets
 
 # add a target to generate API documentation with Doxygen
 # Dependencies: Doxygen and proto2cpp.py
-FIND_PACKAGE(Doxygen)
-set(FILTER_PROTO2CPP_PY_PATH CACHE PATH "directory to the filter proto2cpp.py")
-
-if(NOT DOXYGEN_FOUND)
-
-    message(WARNING  "Doxygen could not be found.")
-
-else()
+find_package(Doxygen)
+if(Doxygen_FOUND)
+    set(FILTER_PROTO2CPP_PY_PATH CACHE PATH "directory to the filter proto2cpp.py")
 
     if(NOT EXISTS ${FILTER_PROTO2CPP_PY_PATH}/proto2cpp.py)
 
@@ -270,4 +265,4 @@ else()
 
     endif(NOT EXISTS ${FILTER_PROTO2CPP_PY_PATH}/proto2cpp.py)
 
-endif(NOT DOXYGEN_FOUND)
+endif()