Use std::optional if available.

Currently, SDK requires C++11 minimum.
So, boost::optional type is used for optional values.
For C++17 and above more convenient is to use std::optional instead.
This PR makes the optional type used configurable.

Fix clang builds.

Relates-To: NLAM-23
Signed-off-by: sopov <ext-alexander.sopov@here.com>

Author: asopov-here

examples/ReadExample.cpp

@@ -204,8 +204,8 @@ int RunExampleRead(const AccessKey& access_key, const std::string& catalog,
   if (!first_partition_id.empty()) {
     // Retrieve the partition data
     // Create a DataRequest with appropriate LayerId and PartitionId
-    auto request = olp::dataservice::read::DataRequest()
-                       .WithPartitionId(first_partition_id);
+    auto request = olp::dataservice::read::DataRequest().WithPartitionId(
+        first_partition_id);
 
     // Run the DataRequest
     auto future = layer_client.GetData(request);

examples/StreamLayerReadExample.cpp

@@ -63,8 +63,7 @@ int GetDataFromMessages(dataread::StreamLayerClient& client,
     auto handle = message.GetMetaData().GetDataHandle();
     if (handle) {
       OLP_SDK_LOG_INFO_F(kLogTag, "Message data: handle - %s, size - %lu",
-                         handle->c_str(),
-                         *message.GetMetaData().GetDataSize());
+                         handle->c_str(), *message.GetMetaData().GetDataSize());
       // use GetData(const model::Message& message) with message instance to
       // request actual data with data handle.
       auto message_future = client.GetData(message);