NetServices: use BBorrow<BDataIO> for custom body targets

Change-Id: Ib2d4b0ca3689338d906f943295278c086c6f2c83

docs/user/netservices/HttpResult.dox

@@ -114,9 +114,8 @@ namespace Network {
 	\brief Represents a HTTP response body.
 	
 	The HTTP response body is captured in this object. The body is either stored into a
-	\ref target, or into a \a text variable, depending on how you called the
-	\ref BHttpSession::Execute() method. If there is a \a target, the body will be empty,
-	and vice versa.
+	target, or into a \ref text variable, depending on how you called the
+	\ref BHttpSession::Execute() method.
 
 	You will usually get a reference to this object through the \ref BHttpResult::Body() method.
 	If you want to keep the contents of the body beyond the lifetime of the BHttpResult object,
@@ -127,17 +126,13 @@ namespace Network {
 
 
 /*!
-	\var std::unique_ptr<BDataIO> BHttpBody::target
-	\brief An owned pointer to where the body has been written.
-
-	\since Haiku R1
-*/
-
-
-/*!
-	\var BString BHttpBody::text
+	\var std::optional<BString> BHttpBody::text
 	\brief A string containing the body of the HTTP request.
 
+	The value of this class variable is set to \c std::nullopt if the target body was written to
+	a specified target. Otherwise, the response body is stored in this string. If the response
+	body was empty, then this will be an empty string.
+
 	\since Haiku R1
 */
 

docs/user/netservices/HttpSession.dox

@@ -165,14 +165,16 @@ namespace Network {
 
 /*!
 	\fn BHttpResult BHttpSession::Execute(BHttpRequest &&request,
-		std::unique_ptr< BDataIO > target=nullptr, BMessenger observer=BMessenger())
+		BBorrow< BDataIO > target=nullptr, BMessenger observer=BMessenger())
 	\brief Schedule and execute a \a request.
 
 	\param request The (valid) request to move from.
 	\param target An optional data buffer to write the incoming body of the request to. This can be
 		\c nullptr if you want to use the default internal storage. If you provide a buffer, it
-		must be wrapped in a \c std::unique_ptr. This means that you transfer ownership to the
-		session. After the request is finished, you can regain ownership.
+		must be wrapped in a \ref BBorrow object. This means that you exclusively borrow the
+		target to this session object. After the request is finished, you can regain usage of the
+		object through the matching \ref BExclusiveBorrow object. Use the \ref BHttpResult::Body()
+		method to synchronize when the target is available again.
 	\param observer An optional observer that will receive the progress and status messages for
 		this request.