💥 Add SASL::Authenticators defaults, by default

Reversed the `use_defaults` default, and added another option for
`use_deprecated`.

lib/net/imap/sasl.rb

@@ -141,9 +141,7 @@ module SASL
       autoload :LoginAuthenticator,       "#{sasl_dir}/login_authenticator"
 
       # Returns the default global SASL::Authenticators instance.
-      def self.authenticators
-        @authenticators ||= Authenticators.new(use_defaults: true)
-      end
+      def self.authenticators; @authenticators ||= Authenticators.new end
 
       # Delegates to ::authenticators.  See Authenticators#authenticator.
       def self.authenticator(...)     authenticators.authenticator(...) end

lib/net/imap/sasl/authenticators.rb

@@ -26,24 +26,23 @@ class Authenticators
     # This class is usually not instantiated directly.  Use SASL.authenticators
     # to reuse the default global registry.
     #
-    # By default, the registry will be empty--without any registrations.  When
-    # +add_defaults+ is +true+, authenticators for all standard mechanisms will
-    # be registered.
-    #
-    def initialize(use_defaults: false)
+    # When +use_defaults+ is +false+, the registry will start empty.  When
+    # +use_deprecated+ is +false+, deprecated authenticators will not be
+    # included with the defaults.
+    def initialize(use_defaults: true, use_deprecated: true)
       @authenticators = {}
-      if use_defaults
-        add_authenticator "Anonymous"
-        add_authenticator "External"
-        add_authenticator "OAuthBearer"
-        add_authenticator "Plain"
-        add_authenticator "Scram-SHA-1"
-        add_authenticator "Scram-SHA-256"
-        add_authenticator "XOAuth2"
-        add_authenticator "Login"      # deprecated
-        add_authenticator "Cram-MD5"   # deprecated
-        add_authenticator "Digest-MD5" # deprecated
-      end
+      return unless use_defaults
+      add_authenticator "Anonymous"
+      add_authenticator "External"
+      add_authenticator "OAuthBearer"
+      add_authenticator "Plain"
+      add_authenticator "Scram-SHA-1"
+      add_authenticator "Scram-SHA-256"
+      add_authenticator "XOAuth2"
+      return unless use_deprecated
+      add_authenticator "Login"      # deprecated
+      add_authenticator "Cram-MD5"   # deprecated
+      add_authenticator "Digest-MD5" # deprecated
     end
 
     # Returns the names of all registered SASL mechanisms.