@Override
    @JsonIgnore
    public String getSelectionStrategy() {
        return strategies.stream()
            .map(RegisteredServiceDelegatedAuthenticationPolicy::getSelectionStrategy)
            .filter(StringUtils::isNotBlank)
            .findFirst()
            .orElse(StringUtils.EMPTY);
    }
Add policy/strategy.

@param policy the provider
core/cas-server-core-services-api/src/main/java/org/apereo/cas/services/ChainingRegisteredServiceDelegatedAuthenticationPolicy.java