Convert extension example to knack (#5093)

doc/extensions/myexampleextension/azext_myexampleextension/__init__.py

@@ -3,7 +3,9 @@
 # Licensed under the MIT License. See License.txt in the project root for license information.
 # --------------------------------------------------------------------------------------------
 
-from azure.cli.core.help_files import helps
+from knack.help_files import helps
+
+from azure.cli.core import AzCommandsLoader
 
 helps['hello world'] = """
     type: command
@@ -13,9 +15,21 @@
 def helloworld():
     print('Hello World.')
 
-def load_params(_):
-    pass
 
-def load_commands():
-    from azure.cli.core.commands import cli_command
-    cli_command(__name__, 'hello world', 'azext_myexampleextension#helloworld')
+class HelloWorldCommandsLoader(AzCommandsLoader):
+
+    def __init__(self, cli_ctx=None):
+        from azure.cli.core.commands import CliCommandType
+        custom_type = CliCommandType(operations_tmpl='azext_myexampleextension#{}')
+        super(HelloWorldCommandsLoader, self).__init__(cli_ctx=cli_ctx,
+                                                       custom_command_type=custom_type)
+
+    def load_command_table(self, args):
+        with self.command_group('hello') as g:
+            g.custom_command('world', 'helloworld')
+        return self.command_table
+
+    def load_arguments(self, _):
+        pass
+
+COMMAND_LOADER_CLS = HelloWorldCommandsLoader

src/azure-cli-core/azure/cli/core/commands/__init__.py

@@ -517,7 +517,7 @@ def _load_command_loader(loader, args, name, prefix):
                     # else:
                     loader.cmd_to_loader_map[cmd] = [command_loader]
     else:
-        logger.debug("Command module '%s' is missing `COMMAND_LOADER_CLS` entry.", name)
+        logger.debug("Module '%s' is missing `COMMAND_LOADER_CLS` entry.", name)
     return command_table