removed notnull attr

Author: petesramek

src/PolylineAlgorithm/Abstraction/AbstractPolylineDecoder.cs

@@ -135,7 +135,7 @@ static void ValidateNullPolyline(TPolyline polyline, ILogger<AbstractPolylineDec
     /// <returns>
     /// A <see cref="ReadOnlyMemory{T}"/> representing the encoded polyline data.
     /// </returns>
-    protected abstract ReadOnlyMemory<char> GetReadOnlyMemory([NotNull]TPolyline polyline);
+    protected abstract ReadOnlyMemory<char> GetReadOnlyMemory(TPolyline polyline);
 
     /// <summary>
     /// Creates a coordinate instance from the given latitude and longitude values.