Fix detecting entities of left join by IEntityDecider (#2385)

Author: hazzik

src/NHibernate/Util/ExpressionsHelper.cs

@@ -6,6 +6,7 @@
 using System.Runtime.CompilerServices;
 using NHibernate.Engine;
 using NHibernate.Linq;
+using NHibernate.Linq.Clauses;
 using NHibernate.Linq.Expressions;
 using NHibernate.Linq.Functions;
 using NHibernate.Linq.Visitors;
@@ -646,6 +647,11 @@ protected override Expression VisitQuerySourceReference(QuerySourceReferenceExpr
 					return base.Visit(joinClause.InnerSequence);
 				}
 
+				if (node.ReferencedQuerySource is NhOuterJoinClause outerJoinClause)
+				{
+					return base.Visit(outerJoinClause.JoinClause.InnerSequence);
+				}
+
 				// Not supported expression
 				_entityName = null;
 				return node;