UseJava.cmake: accept jar targets in add_jar

Modify add_jar to also accepts jars by target name.

Modules/UseJava.cmake

@@ -265,7 +265,14 @@ function(add_jar _TARGET_NAME)
         get_filename_component(_JAVA_PATH ${_JAVA_SOURCE_FILE} PATH)
         get_filename_component(_JAVA_FULL ${_JAVA_SOURCE_FILE} ABSOLUTE)
 
-        if (_JAVA_EXT MATCHES ".java")
+        if (TARGET ${_JAVA_SOURCE_FILE})
+            get_target_property(_JAVA_JAR_PATH ${_JAVA_SOURCE_FILE} JAR_FILE)
+            set(CMAKE_JAVA_INCLUDE_PATH_FINAL "${CMAKE_JAVA_INCLUDE_PATH_FINAL}${CMAKE_JAVA_INCLUDE_FLAG_SEP}${_JAVA_JAR_PATH}")
+            list(APPEND CMAKE_JAVA_INCLUDE_PATH ${_JAVA_JAR_PATH})
+            list(APPEND _JAVA_DEPENDS ${_JAVA_SOURCE_FILE})
+            list(APPEND _JAVA_COMPILE_DEPENDS ${_JAVA_SOURCE_FILE})
+
+        elseif (_JAVA_EXT MATCHES ".java")
             file(RELATIVE_PATH _JAVA_REL_BINARY_PATH ${CMAKE_JAVA_TARGET_OUTPUT_DIR} ${_JAVA_FULL})
             file(RELATIVE_PATH _JAVA_REL_SOURCE_PATH ${CMAKE_CURRENT_SOURCE_DIR} ${_JAVA_FULL})
             string(LENGTH ${_JAVA_REL_BINARY_PATH} _BIN_LEN)