core/src/main/java/org/owasp/encoder/HTMLEncoder.java
static int append(char[] src, char[] out, int j) {
        System.arraycopy(src, 0, out, j, src.length);
        return j + src.length;
    }
static int append(char[] src, char[] out, int j) {
        System.arraycopy(src, 0, out, j, src.length);
        return j + src.length;
    }
Appends a source array verbatim to the output array. Caller must insure
there is enough space in the array for the output.

@param src the characters to copy
@param out the output buffer
@param j the offset where to write in the output buffer
@return {@code j + src.length}