feat: use sfdx's apiversion and loglevel flags

messages/messages.md

@@ -66,6 +66,10 @@ The value must be between %s and %s (inclusive).
 
 Warning:
 
+# warning.loglevel
+
+The loglevel flag is no longer in use on this command. You may use it without error, but it will be ignored.
+
 # actions.tryThis
 
 Try this:

src/compatibility.ts

@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2020, salesforce.com, inc.
+ * All rights reserved.
+ * Licensed under the BSD 3-Clause license.
+ * For full license text, see LICENSE.txt file in the repo root or https://opensource.org/licenses/BSD-3-Clause
+ */
+
+import { Flags } from '@oclif/core';
+import { Messages } from '@salesforce/core';
+import { orgApiVersionFlag } from './flags/orgApiVersion';
+
+/**
+ * Adds an alias for the deprecated sfdx-style "apiversion" and provides a warning if it is used
+ * See orgApiVersionFlag for full details
+ *
+ * @deprecated
+ * @example
+ * ```
+ * import { Flags } from '@salesforce/sf-plugins-core';
+ * public static flags = {
+ *    'api-version': Flags.orgApiVersion({
+ *       char: 'a',
+ *       description: 'api version for the org'
+ *    }),
+ * }
+ * ```
+ */
+export const orgApiVersionFlagWithDeprecations = orgApiVersionFlag({
+  aliases: ['apiversion'],
+  deprecateAliases: true,
+});
+
+Messages.importMessagesDirectory(__dirname);
+const messages = Messages.loadMessages('@salesforce/sf-plugins-core', 'messages');
+/**
+ * Use only for commands that maintain sfdx compatibility.
+ * Flag will be hidden and will show a warning if used.
+ * Flag does *not* set the loglevel
+ *
+ * @deprecated
+ *
+ */
+export const loglevel = Flags.string({
+  hidden: true,
+  deprecated: {
+    message: messages.getMessage('warning.loglevel'),
+  },
+});