private List<ValidationEvent> validateMember(
            StructureShape structure,
            MemberShape member,
            HttpPrefixHeadersTrait prefixTrait
    ) {
        List<ValidationEvent> events = new ArrayList<>();
        String prefix = prefixTrait.getValue().toLowerCase(Locale.ENGLISH);
        Severity severity = Severity.ERROR;
        String detail =
                "`httpHeader` bindings must not case-insensitively start with any `httpPrefixHeaders` bindings.";
        if (StringUtils.isEmpty(prefix)) {
            severity = Severity.NOTE;
            detail = String.format(
                    "The service will not be able to disambiguate between header parameters intended for the `%s` "
                            + "member and those explicitly bound to the `httpHeader` members.",
                    member.getId());
        }

        // Find all structure members that case-insensitively start with the same prefix.
        for (MemberShape otherMember : structure.getAllMembers().values()) {
            if (otherMember.hasTrait(HttpHeaderTrait.ID)) {
                HttpHeaderTrait httpHeaderTrait = otherMember.expectTrait(HttpHeaderTrait.class);
                String lowerCaseHeader = httpHeaderTrait.getValue().toLowerCase(Locale.ENGLISH);

                if (lowerCaseHeader.startsWith(prefix)) {
                    events.add(createEvent(
                            severity,
                            otherMember,
                            httpHeaderTrait,
                            String.format(
                                    "`httpHeader` binding of `%s` conflicts with the `httpPrefixHeaders` binding of `%s` "
                                            + "to `%s`. %s",
                                    lowerCaseHeader,
                                    member.getId(),
                                    prefix,
                                    detail)));
                }
            }
        }

        return events;
    }
Validates that httpHeader traits do not case-insensitively start with an
httpPrefixHeader on the same structure.
smithy-model/src/main/java/software/amazon/smithy/model/validation/validators/HttpPrefixHeadersTraitValidator.java