Fix AppendSuffix to work with different expressions and updated test (#2338)

AppendSuffix should work with any expression instead of just member access expressions
Closes #2331

Author: skncv

src/Nest/CommonAbstractions/Extensions/ExpressionExtensions.cs

@@ -31,7 +31,7 @@ public SuffixExpressionVisitor(string suffix)
 				this.suffix = suffix;
 			}
 
-			protected override Expression VisitMember(MemberExpression node)
+			public override Expression Visit(Expression node)
 			{
 				return Expression.Call(
 					typeof(SuffixExtensions),

src/Tests/ClientConcepts/HighLevel/Inference/FieldInference.doc.cs

@@ -284,7 +284,8 @@ public void AppendingSuffixToExpressions()
 				p => p.Name,
 				p => p.Description,
 				p => p.CuratedTags.First().Name,
-				p => p.LeadDeveloper.FirstName
+				p => p.LeadDeveloper.FirstName,
+				p => p.Metadata["hardcoded"]
 			};
 
 			/** and we want to append the suffix "raw" to each */
@@ -295,6 +296,17 @@ public void AppendingSuffixToExpressions()
 			Expect("description.raw").WhenSerializing(fieldExpressions[1]);
 			Expect("curatedTags.name.raw").WhenSerializing(fieldExpressions[2]);
 			Expect("leadDeveloper.firstName.raw").WhenSerializing(fieldExpressions[3]);
+			Expect("metadata.hardcoded.raw").WhenSerializing(fieldExpressions[4]);
+
+			/** or we might even want to chain multiple `.AppendSuffix()` calls */
+			var multiSuffixFieldExpressions =
+				expressions.Select<Expression<Func<Project, object>>, Field>(e => e.AppendSuffix("raw").AppendSuffix("evendeeper")).ToList();
+
+			Expect("name.raw.evendeeper").WhenSerializing(multiSuffixFieldExpressions[0]);
+			Expect("description.raw.evendeeper").WhenSerializing(multiSuffixFieldExpressions[1]);
+			Expect("curatedTags.name.raw.evendeeper").WhenSerializing(multiSuffixFieldExpressions[2]);
+			Expect("leadDeveloper.firstName.raw.evendeeper").WhenSerializing(multiSuffixFieldExpressions[3]);
+			Expect("metadata.hardcoded.raw.evendeeper").WhenSerializing(multiSuffixFieldExpressions[4]);
 		}
 
 		/**=== Attribute based naming