Also log level Verbose in Diagnostics.Trace or clarify instructions

[monty241]

When extending the custom connectors with trace logging of it's own found the following:

On https://msdn.microsoft.com/en-us/library/mt708848.aspx it describes how you can wrap expression in a function with side-effect that it logs a message to trace.

When enabled in Power BI, you get something like this in your trace:

DataMashup.Trace Information: 24580 : {"Start":"2017-08-18T20:24:11.6486871Z","Action":"Engine/Extension/Invantive.TeamLeader","HostProcessId":"3804","Message":"Invantive: SQL: select * from [Teamleader].[Teamleader].[cost_per_km]","ProductVersion":"2.49.4831.521 (PBIDesktop)","ActivityId":"38a61de4-d0ad-4a8f-bda7-dd4a8fb0aee9","Process":"Microsoft.Mashup.Container.NetFX40","Pid":3720,"Tid":1,"Duration":"00:00:00.0000286"}

But message with Tracelevel verbose are not being logged.

This can be confusing for first time use of developers.

Suggestion is to either document somewhere that you should use Informational or higher, or that include Verbose logging.