The spec defines a search parameter `Group-characteristic-value` of type token, with an expression of `Group.characteristic` and components like this:

[
  {
    "definition": "http://hl7.org/fhir/SearchParameter/Group-characteristic",
    "expression": "code"
  },
  {
    "definition": "http://hl7.org/fhir/SearchParameter/Group-value",
    "expression": "value"
  }
]

This Group-value expression can result in any of the following types:

• CodeableConcept
• boolean
• Quantity
• Range
• Reference

However, the http://hl7.org/fhir/SearchParameter/Group-value search parameter is of type token.

The component expression for the Group-value component should be updated to:

(value as CodeableConcept) | (value as boolean)

See https://chat.fhir.org/#narrow/stream/179166-implementers/topic/Composite.20search.20parameter.20expressions for discussion.