private String doHeaderReplaceAll(String headerValue, String fromRegex, String toReplacement) {
        return headerValue.replaceAll(fromRegex, toReplacement);
    }
Finds all matching instances of the regular expression and replaces them with
the replacement value.
@param headerValue
@param fromRegex
@param toReplacement
gateway/engine/policies/src/main/java/io/apiman/gateway/engine/policies/URLRewritingPolicy.java