Refactor Version::getValue()

Rename the function to getValues() and change the parameter and return
value types, and add a test case for it.
It will be used in future commits.

Tested: Verify the unit test case passes.

Signed-off-by: Lei YU <mine260309@gmail.com>
Change-Id: I57ccf857737ef13f4e2f27c5f2fb7400a2170e91
diff --git a/src/version.hpp b/src/version.hpp
index a67fc82..c3c2c54 100644
--- a/src/version.hpp
+++ b/src/version.hpp
@@ -121,13 +121,13 @@
      *
      * @param[in] filePath - The path to the file which contains the value
      *                       of keys.
-     * @param[in] keys     - A map of keys with empty values.
+     * @param[in] keys     - A vector of keys.
      *
      * @return The map of keys with filled values.
      **/
     static std::map<std::string, std::string>
-        getValue(const std::string& filePath,
-                 std::map<std::string, std::string> keys);
+        getValues(const std::string& filePath,
+                  const std::vector<std::string>& keys);
 
     /** @brief The temUpdater's erase callback. */
     eraseFunc eraseCallback;