Why is ObservableUpDownCounter supported only with .NET 7? #494
Description
I noticed that ObservableUpDownCounter is supported starting from .NET 7. Could you please explain why this is the case? Are there any specific technical limitations or dependencies that prevent its use in earlier versions of .NET?
prometheus-net/Prometheus/MeterAdapter.cs
Line 183 in 60e9106
For example, ObservableUpDownCounter is available in .NET 6. What restricts its functionality or support to .NET 6?