private void printStackTrace(PrintStreamOrWriter s) {
        final StringBuilder b = new StringBuilder(128);
        b.append(this).append('\n');
        for (StackTraceElement myStackElement : getStackTrace()) {
            b.append("\tat ").append(myStackElement).append('\n');
        }
        int i = 1;
        for (Throwable ex : exceptions) {
            b.append("  ComposedException ").append(i).append(" :\n");
            appendStackTrace(b, ex, "\t");
            i++;
        }
        s.println(b.toString());
    }
Special handling for printing out a {@code CompositeException}.
Loops through all inner exceptions and prints them out.

@param s stream to print to
core/src/main/java/com/linecorp/armeria/common/util/CompositeException.java