StepBuilder.Output method fails to map entities

I'm encountering an issue with the Output method in the StepBuilder class. When I try to map an entity (a complex data object), the process fails.

The problem seems to be in the MemberMapParameter constructor. This constructor checks if the value being mapped is accessed using a "member access expression" (e.g., object.property). However, entities are treated as parameters (simple variables) and have a NodeType of Parameter.

Because of this mismatch, the MemberMapParameter constructor throws a "not supported" exception, preventing the mapping of my entity.

Start at StepBuilder.Output and trace how it creates MemberMapParameter for an entity passed as a simple parameter. Reproduce the mapping failure with a complex entity and inspect the constructor's handling of Parameter versus member-access expressions. Done means entity mapping no longer throws the not-supported exception.

Written by the indexing model from the issue text.