fix build

either generator_txt.json needs to be committed or one has to generate
the JSON metadata using kservice_desktop_to_json

generators/txt/CMakeLists.txt

@@ -15,6 +15,7 @@ set(okularGenerator_txt_SRCS
 add_library(okularGenerator_txt MODULE ${okularGenerator_txt_SRCS})
 
 target_link_libraries(okularGenerator_txt okularcore Qt5::Core)
+kservice_desktop_to_json(okularGenerator_txt libokularGenerator_txt.desktop)
 
 install(TARGETS okularGenerator_txt DESTINATION ${PLUGIN_INSTALL_DIR})
 

generators/txt/generator_txt.h

@@ -17,7 +17,7 @@
 class TxtGenerator : public Okular::TextDocumentGenerator
 {
     Q_OBJECT
-    Q_PLUGIN_METADATA(IID OkularGeneratorInterface_iid FILE "generator_txt.json")
+    Q_PLUGIN_METADATA(IID OkularGeneratorInterface_iid FILE "libokularGenerator_txt.json")
 
 public:
     TxtGenerator();