Added Buffer::Buffer(iter, iter) constructor overload

include/cppkafka/buffer.h

@@ -81,6 +81,11 @@ public:
             throw Exception("Invalid buffer configuration");
         }
     }
+    
+    template <typename Iter>
+    Buffer(const Iter first, Iter last)
+    : Buffer(&*first, std::distance(first, last)) {
+    }
 
     /**
      * Constructs a buffer from a vector

include/cppkafka/header_list.h

@@ -260,8 +260,7 @@ HeaderType HeaderList<HeaderType>::at(size_t index) const {
     if (error != RD_KAFKA_RESP_ERR_NO_ERROR) {
         throw Exception(error.to_string());
     }
-    //Use 'Buffer' to implicitly convert to 'BufferType'
-    return HeaderType(name, Buffer(value, size));
+    return HeaderType(name, BufferType(value, value + size));
 }
 
 template <typename HeaderType>