private String resolveFromAuthorizationHeader(HttpHeaders headers) {
        String authorization = headers.getFirst(this.bearerTokenHeaderName);
        if (!StringUtils.startsWithIgnoreCase(authorization, "bearer")) {
            return null;
        }
        Matcher matcher = authorizationPattern.matcher(authorization);
        if (!matcher.matches()) {
            BearerTokenError error = invalidTokenError();
            throw new OAuth2AuthenticationException(error);
        }
        return matcher.group("token");
    }
Set this value to configure what header is checked when resolving a Bearer Token.
This value is defaulted to {@link HttpHeaders#AUTHORIZATION}.

This allows other headers to be used as the Bearer Token source such as
{@link HttpHeaders#PROXY_AUTHORIZATION}
@param bearerTokenHeaderName the header to check when retrieving the Bearer Token.
@since 5.4
zlt-commons/zlt-auth-client-spring-boot-starter/src/main/java/com/central/oauth2/common/component/CustomServerBearerTokenAuthConverter.java