dstIndex += this.scope.length();

        dst[dstIndex++] = (byte) 0x00;

        // now go over scope backwards converting '.' to label length

        int i = dstIndex - 2;
        final int e = i - this.scope.length();
        int c = 0;

        do {
            if (dst[i] == '.') {

        if (typeof options.applyClass === 'string') //backwards compat
            this.applyButtonClasses = options.applyClass;

        if (typeof options.cancelButtonClasses === 'string')
            this.cancelButtonClasses = options.cancelButtonClasses;

        if (typeof options.cancelClass === 'string') //backwards compat
            this.cancelButtonClasses = options.cancelClass;

 *  New: `OkHttpClient.Builder` now has APIs that use `kotlin.time.Duration`.

 *  New: `mockwebserver3.SocketPolicy` is now a sealed interface. This is one of several
    backwards-incompatible API changes that may impact early adopters of this alpha API.

 *  New: `mockwebserver3.Stream` for duplex streams.

 *  New: `mockwebserver3.MockResponseBody` for streamed response bodies.

                : new NonTerminalImmutableMapEntry<K, V>(key, value, keyBucketHead);
        table[tableIndex] = effectiveEntry;
      } else {
        // We already saw this key, and the first value we saw (going backwards) is the one we are
        // keeping. So we won't touch table[], but we do still want to add the existing entry that
        // we found to entries[] so that we will see this key in the right place when iterating.

        .cipherSuites(*APPROVED_CIPHER_SUITES.toTypedArray())
        .tlsVersions(TlsVersion.TLS_1_3, TlsVersion.TLS_1_2)
        .supportsTlsExtensions(true)
        .build()

    /**
     * A backwards-compatible fallback configuration that works on obsolete client platforms and can
     * connect to obsolete servers. When possible, prefer to upgrade your client platform or server
     * rather than using this configuration.

---
title: "Go, Backwards Compatibility, and GODEBUG"
layout: article
---

<!--
This document is kept in the Go repo, not x/website,
because it documents the full list of known GODEBUG settings,
which are tied to a specific release.
-->

## Introduction {#intro}

Go's emphasis on backwards compatibility is one of its key strengths.
There are, however, times when we cannot maintain complete compatibility.

/*
Package zip provides support for reading and writing ZIP archives.

See the [ZIP specification] for details.

This package does not support disk spanning.

A note about ZIP64:

To be backwards compatible the FileHeader has both 32 and 64 bit Size
fields. The 64 bit fields will always contain the correct value and
for normal archives both fields will be the same. For files requiring

    // * The element with (index == from) should be kept.
    // * Everything with (index > from) has not been checked yet.

    // Check from the end of the list backwards (minimize expected cost of
    // moving elements when remove() is called). Stop before 'from' because
    // we already know that should be kept.
    for (int n = list.size() - 1; n > from; n--) {

    they could leak passwords and other authentication credentials to insecure
    logs.

 *  **WebSocket API now uses `RequestBody` and `ResponseBody` for messages.**
    This is a backwards-incompatible API change.

 *  **The DNS service is now pluggable.** In some situations this may be useful
    to manually prioritize specific IP addresses.

        // First byte should be length of "test" (4) after processing
        assertEquals(4, dst[0]);

        // After processing, dots should be replaced with length markers
        // The scope processing happens backwards
        assertEquals(name.scope.length() + 2, length);
    }

    @Test
    void readScopeWireFormat_withMultipleLabels_shouldParseCorrectly() {
        byte[] src = new byte[100];