protected void encodeDOUBLE(double value) {
            if (Double.isFinite(value)) {
                out.append(value);
            } else {
                out.append("null");
            }
        }
Renders the given value to the target stringbuilder with a given encoder.
This is useful to use an encoder where rendering of some value types is customized.
vespajlib/src/main/java/com/yahoo/data/access/simple/JsonRender.java