Build with --features R6 fails: missing crate::r6 module

[qazah]

When trying to build the project with the R6 feature enabled, the compilation fails because the r6 module is missing.

cargo build --release --features R6

error[E0433]: failed to resolve: could not find `r6` in the crate root
  --> crates\fhir\src\parameters.rs:64:15
   |
64 |     R6(crate::r6::Parameters),
   |               ^^ could not find `r6` in the crate root

error[E0433]: failed to resolve: could not find `r6` in the crate root
   --> crates\fhir\src\parameters.rs:231:40
    |
231 | impl ParameterValueAccessor for crate::r6::ParametersParameterValue {
    |                                        ^^ could not find `r6` in the crate root

error[E0433]: failed to resolve: could not find `r6` in the crate root
   --> crates\fhir\src\parameters.rs:234:20
    |
234 |             crate::r6::ParametersParameterValue::String(s) => s.value.as_deref(),
    |                    ^^ could not find `r6` in the crate root

Expected behavior:
The project should build successfully with the R6 feature, or the README should clarify that R6 is not yet supported/implemented.

Environment:

OS: Windows 10 (x86_64-pc-windows-msvc)
rustc 1.90.0 (1159e78c4 2025-09-14)

[smunini]

Thank you - we are aware of this issue and will work on a fix. In the meantime, the other FHIR versions will build with this command:
cargo build --release --features R4,R4B,R5

[smunini]

https://chat.fhir.org/#narrow/channel/179166-implementers/topic/TestPlan.20use.20of.20'Base'/with/541102959

[smunini]

This should be fixed in fix/R6-build-fails