Bugfix/issue 8101

[tonydnewell]

Fix for #8101

When converting identifiers for C# camel case, handle the case where the input starts with "_<digit>" and preserve the underscore.

It does not alter existing behaviour for other identifiers:

• e.g. starts with "_<alpha>" - the underscore is consumed, so as to not break anything that relies on existing behaviour.
• e.g. input is already invalid (e.g. identifier starts with a digit) - it does not try and fix it.

[jtattermusch]

LGTM as well.

[nickwinger]

@tonydnewell thank you for this fix, but on our side there is still a similar bug open with this, e.g.: namespace "my.space._3" gets compiled to c# "my.space.3" which again causes an error. So also with "sub" namespaces after dots the numbers with an underscore should be preserved. thank you

[tonydnewell]

@nickwinger Thank you for your observation. I can see you've created a new issue #13482
I can't guarantee when it will be fixed but it is on the list.

[nickwinger]

here is the PR: #13504