public String getResolvedHeaderValue(ApiRequest request) {
        String rVal = null;

        switch (getValueType()) {
        case ENV:
            rVal = System.getenv(headerValue);
            break;
        case SYS:
            rVal = System.getProperty(headerValue);
            break;
        case STRING:
            rVal = headerValue;
            break;
        case HEADER:
            if(request == null) {
                throw new IllegalArgumentException("Invalid access when reading header value.");
            }
            rVal = request.getHeaders().get(headerValue);
            break;
        }

        return (rVal == null) ? "" : rVal;
    }
Overwrite Existing
<p>


@param overwrite The overwrite
plugins/simple-header-policy/src/main/java/io/apiman/plugins/simpleheaderpolicy/beans/AddHeaderBean.java