@Override
    protected void doApply(ApiRequest request, IPolicyContext context, UniqueHeaderBean config,
                           IPolicyChain<ApiRequest> chain) {

        handleHeader(request.getHeaders(), context, config);
        chain.doApply(request);
    }
@see io.apiman.gateway.engine.policies.AbstractMappedPolicy#doApply(io.apiman.gateway.engine.beans.ApiRequest, io.apiman.gateway.engine.policy.IPolicyContext, java.lang.Object, io.apiman.gateway.engine.policy.IPolicyChain)
plugins/unique-header-policy/src/main/java/io/apiman/plugins/uniqueheader/UniqueHeaderPolicy.java