PSUseOutputTypeCorrectly is triggered when it shouldn't.

It looks to me like PSUseOutputTypeCorrectly check is not taking very basic, crucial, fundamental fact about PowerShell into account: by default it will not keep any simple collection, unless you explicitly tell it to.

Result? I have PInvoke code (taken from here) and I correctly defined OutputType as [Connection] (I've actually created namespace for it, but that's irrelevant).
As expected, Get-Member confirms that PowerShell function will return stream of connections, not collection as a whole. Yet, PSScriptAnalyzer will complain about it:

Line: 45 - The cmdlet 'Get-OPNetStat' returns an object of type 'Optiver.Connection[]' but this type is not declared in the OutputType attribute. 
Line: 54 - The cmdlet 'Get-OPNetStat' returns an object of type 'Optiver.Connection[]' but this type is not declared in the OutputType attribute. 

In fact, if I would follow instructions and declare my OutputType as a collection it would be conflicting with what my function actually returns:

Set-StrictMode -Version Latest
Get-OPNetStat | % IsFixedSize
% : The input name "IsFixedSize" cannot be resolved to a member.

IsFixedSize was tab-completed, based on OutputType that PSScriptAnalyzer told me to define. As expected, my Connection object doesn't have it. The only workaround I've found that satisfies both PSScriptAnalyzer and my hope to get nice tab-completion for command I wrote is to pass result of the command thru ForEach-Object:

[Optiver.NetworkUtil]::GetTCP() } | ForEach-Object { $_ }

Start with the PSUseOutputTypeCorrectly rule and reproduce the reported Get-OPNetStat example, including the [Optiver.NetworkUtil]::GetTCP() output and Get-Member behavior. Compare the declared [Connection] output type with the analyzer's Connection[] diagnostic; done means valid stream output no longer produces this false warning while output-type tab completion remains accurate.