[Linting & Validation] expression fields in arrays do not get validated

[a-b-r-o-w-n]

For instance, DeleteProperties.items.property does not get validated as an expression.

[a-b-r-o-w-n]

Upon some investigation, the function getExpressionProperties does not get all of the properties that need to be validated as expressions so these are not getting picked up.

[cwhitten]

addressed via #1798