CSHARP-5507: Improve readability of some conventions code (#1622)

Author: papafe

src/MongoDB.Bson/Serialization/Conventions/EnumRepresentationConvention.cs

@@ -70,7 +70,7 @@ public void Apply(BsonMemberMap memberMap)
         {
             var memberType = memberMap.MemberType;
 
-            if (!(memberType.IsEnum || memberType.IsNullableEnum() || memberType.IsArray || typeof(IEnumerable).IsAssignableFrom(memberType)))
+            if (!CouldApply(memberType))
             {
                 return;
             }
@@ -87,6 +87,9 @@ public void Apply(BsonMemberMap memberMap)
 
             IBsonSerializer Reconfigure(IBsonSerializer s)
                 => s.ValueType.IsEnum ? (s as IRepresentationConfigurable)?.WithRepresentation(_representation) : null;
+
+            bool CouldApply(Type type)
+                => type.IsEnum || type.IsNullableEnum() || type.IsArray || typeof(IEnumerable).IsAssignableFrom(type);
         }
 
         // private methods

src/MongoDB.Bson/Serialization/Conventions/ObjectSerializerAllowedTypesConvention.cs

@@ -155,8 +155,7 @@ public void Apply(BsonMemberMap memberMap)
         {
             var memberType = memberMap.MemberType;
 
-            if (memberType != typeof(object) && Nullable.GetUnderlyingType(memberType) == null && !memberType.IsArray &&
-                !typeof(IEnumerable).IsAssignableFrom(memberType))
+            if (!CouldApply(memberType))
             {
                 return;
             }
@@ -168,8 +167,12 @@ public void Apply(BsonMemberMap memberMap)
             {
                 memberMap.SetSerializer(reconfiguredSerializer);
             }
+
+            bool CouldApply(Type type)
+                => type == typeof(object) || type.IsNullable() || type.IsArray || typeof(IEnumerable).IsAssignableFrom(type);
         }
 
+        // private methods
         private IBsonSerializer Reconfigure(IBsonSerializer serializer)
         {
             if (serializer is IChildSerializerConfigurable childSerializerConfigurable)