Documented naming conventions of when we use different class suffixes, like 'Manager', 'Client', 'Utilities', etc. (#2602)

Author: millems

docs/design/NamingConventions.md

@@ -4,14 +4,34 @@
 
 This page describes the naming conventions, nouns and common terms 
 
-- Abbreviations must follow the same conventions as any other word (eg. use `DynamoDbClient`, not `DynamoDBClient`)
+### Class Naming
 
-- Use Singular Enum Name
-
-  For enum classes or "pseudo-enums" classes(classes with public static fields), we should use singular name. (eg. use `SdkSystemSetting`, not `SdkSystemSettings`)
+#### General Rules
+* Prefer singular class names: `SdkSystemSetting`, not `SdkSystemSettings`.
+* Treat acronyms as a single word: `DynamoDbClient`, not `DynamoDBClient`.
 
-- Use of `Provider`, `Supplier` and `Factory` in the class name.
-  - For general supplier classes (loading/creating resources of the same kind), prefer `Provide` unless the class extends from Java `Supplier` class. (eg. `AwsCredentialsProvider`)
-  - For factories classes (creating resources of same or different kinds), prefer  `Factory`. (eg. `AwsJsonProtocolFactory`)
- 
+#### Classes that instantiate other classes
+
+* If the class's primary purpose is to return instances of another class:
+  * If the "get" method has no parameters:
+    * If the class implements `Supplier`: `{Noun}Supplier` (e.g. `CachedSupplier`)
+    * If the class does not implements `Supplier`: `{Noun}Provider` (e.g. `AwsCredentialsProvider`)
+  * If the "get" method has paramters: `{Noun}Factory` (e.g. `AwsJsonProtocolFactory`)
+
+#### Service-specific classes
 
+* If the class makes service calls:
+  * If the class can be used to invoke *every* data-plane operation:
+    * If the class is code generated:
+      * If the class uses sync HTTP: `{ServiceName}Client` (e.g. `DynamoDbClient`)
+      * If the class uses async HTTP: `{ServiceName}AsyncClient` (e.g. `DynamoDbAsyncClient`)
+    * If the class is hand-written:
+      * If the class uses sync HTTP: `{ServiceName}EnhancedClient` (e.g. `DynamoDbEnhancedClient`)
+      * If the class uses async HTTP: `{ServiceName}EnhancedAsyncClient` (e.g. `DynamoDbEnhancedAsyncClient`)
+  * If the class can be used to invoke only *some* data-plane operations:
+    * If the class uses sync HTTP: `{ServiceName}{Noun}Manager` (e.g. `SqsBatchManager`)
+    * If the class uses async HTTP: `{ServiceName}Async{Noun}Manager` (e.g. `SqsAsyncBatchManager`)
+    * Note: If only the only implementation uses async HTTP, `Async` may be excluded. (e.g. `S3TransferManager`)
+* If the class does not make service calls:
+  * If the class creates presigned URLs: `{ServiceName}Presigner` (e.g. `S3Presigner`)
+  * If the class is a collection of various unrelated "helper" methods: `{ServiceName}Utilities` (e.g. `S3Utilities`)