'metadata' top-level property rejected on resources

[stuartko]

Currently 'metadata' is a supported property in ARM templates for storing customer metadata of any type (it's effectively ignored by ARM). In Bicep, specifying metadata in the top-level resource results in a rejection:

Error BCP037: The property 'metadata' is not allowed on objects of type 'Microsoft.Storage/storageAccounts@2019-04-01'.

[alex-frankel]

@stuartko - do you remember why you needed this? We're thinking about continuing to not allow it

[stuartko]

Mostly just to keep parity with ARM templates (to allow decompile to work and be lossless). I’ve seen a few enterprise customers using it while I’ve investigated past incidents. If we do not think parity with ARM is critical I think it should be safe to drop.

[stweb1963]

We use the metadata as a documentation source to generate markdown of our templates

Combined with templateSpecs, versioning, tags, etc. this is a very convenient method of generating markdown

All our current templates have mandatory metadata on parameters and outputs for this very reason
Because bicep disallows, we loose this ability to auto document our outputs

[bmoore-msft]

Portal also uses it... since json supports it (in various places) bicep should too...

[anthony-c-martin]

Related: #1665