On this page it states:

• There are hard-coded workspace checks in DefaultTemplateAvailability and ConfiguredSiteTemplateAvailability. (See MGNLSITE-161 for more details.)
• The example project works around this with a custom availability (info.magnolia.custom.availability.CustomSiteTemplateAvailability).

This is outdated - since 6.2.38.

Please change to:

• Until Magnolia 6.2.38 There were hard-coded workspace checks in DefaultTemplateAvailability and ConfiguredSiteTemplateAvailability. (See MGNLSITE-161 for more details.)
• The example project works around this with a custom availability (info.magnolia.custom.availability.CustomSiteTemplateAvailability).

• In 6.2.38+ the custom availabiilty class is no longer needed.