public void set(int index, String value) {
            verifyIndex();
            ConfigPayloadBuilder p = new ConfigPayloadBuilder(value);
            elements.put(index, p);
        }
Set the value of array element index to value

@param index Index of array element to set.
@param value Value that the element should point to.
config/src/main/java/com/yahoo/vespa/config/ConfigPayloadBuilder.java