Fix reorder error in maintainer mode

Author: chusitoo

api/include/opentelemetry/context/context.h

@@ -94,13 +94,13 @@ class Context
   {
     char *key_ = nullptr;
 
-    nostd::shared_ptr<DataList> next_;
+    nostd::shared_ptr<DataList> next_{nullptr};
 
     size_t key_length_ = 0UL;
 
     ContextValue value_;
 
-    DataList() : next_{nullptr} {}
+    DataList() = default;
 
     // Builds a data list off of a key and value iterable and returns the head
     template <class T>