source/time: Fix missing documentation

Documentation was accidentally left out of this class

Change-Id: I977caf9fbb716f2fcb3510f722712fdf695441b7
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/src/sdeventplus/source/time.hpp b/src/sdeventplus/source/time.hpp
index 28a42fb..14d4304 100644
--- a/src/sdeventplus/source/time.hpp
+++ b/src/sdeventplus/source/time.hpp
@@ -16,25 +16,77 @@
 class Time : public Base
 {
   public:
+    /** @brief Type used as the basis for absolute clock times */
     using TimePoint = typename Clock<Id>::time_point;
+    /** @brief Type used to define the accuracy of the time source */
     using Accuracy = SdEventDuration;
+    /** @brief Type of the user provided callback function */
     using Callback = std::function<void(Time& source, TimePoint time)>;
 
+    /** @brief Creates a new time event source on the provided event loop
+     *
+     *  @param[in] event    - The event to attach the handler
+     *  @param[in] time     - Absolute time when the callback should be executed
+     *  @param[in] accuracy - Optional amount of error tolerable in time source
+     *  @param[in] callback - The function executed on event dispatch
+     */
     Time(const Event& event, TimePoint time, Accuracy accuracy,
          Callback&& callback);
 
+    /** @brief Gets the absolute time when the time source expires
+     *
+     *  @throws SdEventError for underlying sd_event errors
+     *  @return Absolute time as an std::chrono::time_point
+     */
     TimePoint get_time() const;
+
+    /** @brief Sets the absolute time when the time source will expire
+     *
+     *  @param[in] time - Absolute time as an std::chrono::time_point
+     *  @throws SdEventError for underlying sd_event errors
+     */
     void set_time(TimePoint time) const;
+
+    /** @brief Gets the accuracy of the time source
+     *
+     *  @throws SdEventError for underlying sd_event errors
+     *  @return Accuracy as an std::chrono::duration
+     */
     Accuracy get_accuracy() const;
+
+    /** @brief Sets the accuracy of the time source
+     *
+     *  @param[in] accuracy - Accuracy as std::chrono::duration
+     *  @throws SdEventError for underlying sd_event errors
+     */
     void set_accuracy(Accuracy accuracy) const;
 
   private:
     Callback callback;
 
+    /** @brief Returns a reference to the callback executed for this source
+     *
+     *  @return A reference to the callback
+     */
     const Callback& get_callback() const;
 
+    /** @brief Creates a new time source attached to the Event
+     *
+     *  @param[in] event    - The event to attach the handler
+     *  @param[in] time     - Absolute time when the callback should be executed
+     *  @param[in] accuracy - Optional amount of error tolerable in time source
+     *  @throws SdEventError for underlying sd_event errors
+     *  @return A new sd_event_source
+     */
     static sd_event_source* create_source(const Event& event, TimePoint time,
                                           Accuracy accuracy);
+
+    /** @brief A wrapper around the callback that can be called from sd-event
+     *
+     *  @param[in] source   - The sd_event_source associated with the call
+     *  @param[in] userdata - The provided userdata for the source
+     *  @return 0 on success or a negative errno otherwise
+     */
     static int timeCallback(sd_event_source* source, uint64_t usec,
                             void* userdata);
 };