String[] (@NotNull String[] a1, @NotNull String[] a2) { if (a1.length == 0) return a2; if (a2.length == 0) return a1; String[] result = new String[a1.length + a2.length]; System.arraycopy(a1, 0, result, 0, a1.length); System.arraycopy(a2, 0, result, a1.length, a2.length); return result; }