Release v4.204.0

Read models can now have a composite key made of several key properties, and such models bind and run in the executable model.

Added

• Read models with two or more key properties bind and execute: projections key root from blocks with a key block naming every part, list queries narrow them with equality filters, and an optional single-instance query looks one up with a by block naming every part. Models that use them select ESM v27; every other model keeps its version and bytes. See decision 0088. (#599)
• remove with accepts a key block with one part = expr line per key part, so a composite-keyed instance can be removed and later recreated. (#599)
• Specifications state every key part in given readmodel, then readmodel and then no readmodel, and query arguments supply every by part; a missing part is reported as PLAY0661 and an unknown or ill-typed part as PLAY0662. (#599)

Changed

• Joins, children, remove via join, every, all, nested, clear with, variant and reducers on a composite-keyed read model, and list queries with a by block over one, are refused with PLAY0268 instead of the whole read model being refused. (#599)