chore: import upstream snapshot with attribution

modules/java/jar/list_java_sources.cmake

@@ -0,0 +1,19 @@
+file(GLOB_RECURSE java_sources "${OPENCV_JAVA_DIR}/*.java")
+
+set(__sources "")
+
+foreach(dst ${java_sources})
+    set(__sources "${__sources}${dst}\n")
+endforeach()
+
+function(ocv_update_file filepath content)
+  if(EXISTS "${filepath}")
+    file(READ "${filepath}" actual_content)
+  else()
+    set(actual_content "")
+  endif()
+  if(NOT ("${actual_content}" STREQUAL "${content}"))
+    file(WRITE "${filepath}" "${content}")
+  endif()
+endfunction()
+ocv_update_file("${OUTPUT}" "${__sources}")