Apply suggestions from code review

Co-Authored-By: Jacob Perron <jacob@openrobotics.org>
Co-Authored-By: William Woodall <william+github@osrfoundation.org>
Signed-off-by: Michael Carroll <michael@openrobotics.org>

rmw/include/rmw/message_sequence.h

@@ -52,7 +52,7 @@ typedef struct RMW_PUBLIC_TYPE rmw_message_info_sequence_t
   rcutils_allocator_t * allocator;
 } rmw_message_info_sequence_t;
 
-/// Return an rmw_message_sequence_t struct with members initialized to `NULL`;
+/// Return an rmw_message_sequence_t struct with members initialized to `NULL`
 RMW_PUBLIC
 rmw_message_sequence_t
 rmw_get_zero_initialized_message_sequence(void);
@@ -74,7 +74,7 @@ rmw_message_sequence_init(
 /**
  * The rmw_message_sequence_t struct has members which require memory to be allocated to them
  * before setting values.
- * This function reclaims any allocated resources within the obect and zeroes out all other
+ * This function reclaims any allocated resources within the object and zeroes out all other
  * members.
  *
  * Note: This will not call `fini` or deallocate the underlying message structures.

rmw/include/rmw/rmw.h

@@ -717,7 +717,7 @@ rmw_take_with_info(
  *
  * While `count` messages may be requested, fewer messages may be available on the subscription.
  * In this case, only the currently available messages will be returned.
- * The `taken` flag indicate the number of messages actually taken.
+ * The `taken` flag indicates the number of messages actually taken.
  * The method will return `RMW_RET_OK` even in the case that fewer (or zero) messages retrieved
  * from the subscription, and will `RMW_RET_ERROR` in the case of unexpected errors.
  * In the case that `count` is zero, the function will return `RMW_RET_INVALID_ARGUMENT`.
@@ -728,14 +728,14 @@ rmw_take_with_info(
  *
  * \param[in] subscription The subscription object to take from.
  * \param[in] count Number of messages to attempt to take.
- * \param[out] message_sequence The sequence ROS message data on success.
+ * \param[out] message_sequence The sequence of ROS message data on success.
  * \param[out] message_info_sequence The sequence of additional message metadata on success.
  * \param[out] taken Number of messages actually taken from subscription.
  * \param[in] allocation Preallocated buffer to use (may be NULL).
  * \return `RMW_RET_OK` if successful, or
  * \return `RMW_RET_INVALID_ARGUMENT` if an argument is invalid, or
  * \return `RMW_RET_BAD_ALLOC` if memory allocation failed, or
- * \return `RMW_RET_INCORRECT_RMW_IMPLEMENTATION` if the subscription is invalid, or
+ * \return `RMW_RET_INCORRECT_RMW_IMPLEMENTATION` if the rmw implementation does not match, or
  * \return `RMW_RET_ERROR` if an unexpected error occurs.
  */
 RMW_PUBLIC

rmw/src/message_sequence.c

@@ -21,7 +21,8 @@ rmw_get_zero_initialized_message_sequence(void)
   static rmw_message_sequence_t message_sequence = {
     .data = NULL,
     .size = 0u,
-    .capacity = 0u
+    .capacity = 0u,
+    .allocator = NULL
   };
 
   return message_sequence;