public static IMongoQueryable<TResult> GroupJoin<TOuter, TInner, TKey, TResult>(
	this IMongoQueryable<TOuter> outer,
	IEnumerable<TInner> inner,
	Expression<Func<TOuter, TKey>> outerKeySelector,
	Expression<Func<TInner, TKey>> innerKeySelector,
	Expression<Func<TOuter, IEnumerable<TInner>, TResult>> resultSelector
)

<ExtensionAttribute>
Public Shared Function GroupJoin(Of TOuter, TInner, TKey, TResult) ( 
	outer As IMongoQueryable(Of TOuter),
	inner As IEnumerable(Of TInner),
	outerKeySelector As Expression(Of Func(Of TOuter, TKey)),
	innerKeySelector As Expression(Of Func(Of TInner, TKey)),
	resultSelector As Expression(Of Func(Of TOuter, IEnumerable(Of TInner), TResult))
) As IMongoQueryable(Of TResult)

[<ExtensionAttribute>]
static member GroupJoin : 
        outer : IMongoQueryable<'TOuter> * 
        inner : IEnumerable<'TInner> * 
        outerKeySelector : Expression<Func<'TOuter, 'TKey>> * 
        innerKeySelector : Expression<Func<'TInner, 'TKey>> * 
        resultSelector : Expression<Func<'TOuter, IEnumerable<'TInner>, 'TResult>> -> IMongoQueryable<'TResult>