ComInterfaceGenerator provides confusing warning for arrays with [InAttribute]

[jtschuster]

When [InAttribute] is applied to an array, the generators will warn with a confusing warning

SYSLIB1051: The '[In]' attribute is not supported unless the '[Out]' attribute 
is also used. The behavior of the '[In]' attribute without the '[Out]' attribute 
is the same as the default behavior. The generated source will not handle 
marshalling of parameter 'paramName'.

The statement The behavior of the '[In]' attribute without the '[Out]' attribute is the same as the default behavior. is not true for arrays; the default behavior is [In, Out]

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Issue Details

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When [InAttribute] is applied to an array, the generators will warn with a confusing warning

SYSLIB1051: The '[In]' attribute is not supported unless the '[Out]' attribute 
is also used. The behavior of the '[In]' attribute without the '[Out]' attribute 
is the same as the default behavior. The generated source will not handle 
marshalling of parameter 'paramName'.

The statement The behavior of the '[In]' attribute without the '[Out]' attribute is the same as the default behavior. is not true for arrays; the default behavior is [In, Out]

Author:	jtschuster
Assignees:	jtschuster
Labels:	area-System.Runtime.InteropServices
Milestone:	8.0.0