Protocol Buffers 28.0

What's new in this version:

Compiler:
- UPB text encoder without using reflection for Rust
- Enable MessageLite::DebugString to use Message::DebugString where possible
- Always report plugin support errors from protoc.
- Stop supporting EDITION_PROTO2 as an alias for EDITION_LEGACY
- Rename DynamicCastToGenerated/DownCastToGenerated to
- Mark deleted fields in descriptor.proto reserved
- Protoc: support inf, -inf, nan, and -nan in option values

C++:
- Move -Werror to our test/dev bazelrc files.
- Introduce FieldDescriptor::cpp_string_type() API to replace direct ctype inspection which will be removed in the next breaking change
- Removed specific MSVC settings when installing
- Omit the _raw_default_instance_ declaration when using DLL linkage
- Enable MessageLite::DebugString to use Message::DebugString where possible
- Fix a bug in which proto code uses ctype instead of string_type internally
- Add an optimization that prevents an exponential number of comparisons on deeply
- Replace FindHelper() with BucketNumber() when only the bucket number is required
- Stop supporting EDITION_PROTO2 as an alias for EDITION_LEGACY
- Rename DynamicCastToGenerated/DownCastToGenerated to
- Prohibit using features in the same file they're defined in
- Implement new Debug API with redaction
- Use bool HasHasbits(const FieldDescriptor*) instead of manual checks
- Add java to reserved names to escape extensions to java_. This may break existing references to gencode for extensions named java.
- Put arena cleanup nodes on a separate chunked list instead of at the ends of arena blocks
- Fix validation checks of implicit presence
- Clarify map behaviors in editions
- Protoc: support inf, -inf, nan, and -nan in option values

Java:
- Binary compatibility shims for GeneratedMessageV3, SingleFieldBuilderV3, RepeatedFieldBuilderV3, and their nested classes to restore binary compatibility with <=v3.x.x generated code built against v3.x.x prior to v4.26.0 breaking release.
- Remove unused pom.xml files.
- Add overload for LazyStringArrayList.add(String): boolean
- Hoist SmallSortedMap.getNumArrayEntries() outside loops over array entries
- Omit the _raw_default_instance_ declaration when using DLL linkage
- Java: Deprecate newExtensionWriter
- Immutable java: Use new lower-allocation extension serialization APIs from gencode
- Reserialize all unresolved features using java features from the generated pool in case of descriptors from the custom pool.
- Fix delimited inheritance in all languages
- Full java runtime: Avoid allocating ArrayList iterators when serializing UnknownFieldSet
- Move back deprecation of java utf8 feature to 2024
- Reparse unknown features using extension registry containing Java features
- Remove field SmallSortedMap.maxArraySize
- Delete unused method SmallSortedSet.getOverflowEntriesDescending
- Avoid allocating FieldSet iterator if FieldSet is empty
- Lazily resolve features for proto2 and proto3 for compatibility with old open source gencode that does not invoke feature resolution from gencode static init
- Implement new Debug API with redaction
- Replace SmallSortedMap.EmptySet with equivalent Collections.emptySet()
- Add java to reserved names to escape extensions to java_. This may break existing references to gencode for extensions named java.
- Avoid allocating TreeMap in UnknownFieldSet.Builder.asMap
- Avoid allocating iterator in TextFormat printing UnknownFieldSet
- Add null to the list of reserved words
- Add UnknownFieldSet.isEmpty
- Java full runtime: Avoid allocating when calling asMap on empty UnknownFieldSet
- Return the default instance when parsing from an empty byte[]
- Deprecate building from source with Maven to be removed in 4.28.x
- Java full runtime: Avoid allocating iterator if UnknownFieldSet's TreeMap is empty
- Proto java full runtime: avoid allocating Integers accessing enum lists
- Split bootstrapped java_features.proto to keep it from leaking out
- Java Proto lite: avoid boxing Integers accessing enum lists
- In the Kotlin DSL, reference builder methods with property syntax
- Java Proto Lite: Serialize repeated enums without allocating
- Avoid boxing when serializing primitive lists in CodedOutputStreamWriter

Kotlin:
- Remove unused pom.xml files.
- In the Kotlin DSL, reference builder methods with property syntax

Csharp:
- Fix delimited inheritance in all languages
- Handle groups in C# JsonParser
- Introduce MessageDescriptor.IsMapType in C# reflection to make it easier to tell whether a given message was generated by protoc for a map field
- C#: Fix discovery of oneof declarations in descriptor protos

Objective-C:
- [ObjC] Issue stderr warnings for deprecated generation options
- [ObjC] Add api to add a field to another collection of unknown fields
- [ObjC] Fix GPBUnknownField/GPBUnknownFields copy
- [ObjC] Raise an exception for a nil message
- [ObjC] Deprecate GPBUnknownFieldSet and related apis
- [ObjC] More tests around unknown to known failure cases
- [ObjC] Support errors when merging unknown fields to a message
- [ObjC] Add apis for removing things from GPBUnknownFields
- [ObjC] Collect unknown fields as data
- [ObjC] Internal helper for getting the unknown field data from a message
- [ObjC] Update tests to use both unknown fields apis
- [ObjC] Deprecate GPBTextFormatForUnknownFieldSet()
- [ObjC] Parsing helper and tests around unknown fields
- [ObjC] Add test around enum unknown values
- [ObjC] Expose a helper for stream error
- [ObjC] Support MessageSet with GPBUnknownFields
- [ObjC] Update MessageSet Parsing
- [ObjC] Validate MessageSet expectations
- [ObjC] Improve parsing validations
- [ObjC] Add Swift helpers for GPBUnknownFields/GPBUnknownField
- [ObjC] Introduce the new GPBUnknownFields type
- Rename DynamicCastToGenerated/DownCastToGenerated to

Rust:
- Move -Werror to our test/dev bazelrc files
- Add visibility for rust public aliases for '@protobuf//:protobuf_rust'
- UPB text encoder without using reflection for Rust
- Enable MessageLite::DebugString to use Message::DebugString where possible
- See also UPB changes below, which may affect Rust

Python:
- Raise warnings for deprecated python cpp extension GetDebugString()
- Remove service.py usages in builder
- Raise warnings for deprecated google/protobuf/reflection.py APIs
- Nextgen Proto Pythonic API: Struct/ListValue assignment and creation
- Fix delimited inheritance in all languages
- Make bytearray work
- Nextgen Proto Pythonic API: Timestamp/Duration assignment, creation and calculation
- Update rules_python to 0.28.0
- Nextgen Proto Pythonic API: “Add-on” proto for length prefixed serialize/parse
- Rename DynamicCastToGenerated/DownCastToGenerated to
- Fixed printing of nan floats/doubles in Python.
- Nextgen Proto Pythonic API: “Add-on” proto for JSON serialize/parse
- Nextgen Proto Pythonic API: “Add-on” proto for serialize/parse
- Use struct instead of ctype. allows the protobuf python library to work on cpython 3.11's new wasm target [1]
- Nextgen Proto Pythonic API: Add 'in' operator
- Automated rollback of commit f799af8
- Catch all the exceptions in python JSON ParseDict and raise

PHP:
- Chore(php): conformance testing for edition

PHP C-Extension:
- Fix segmentation faults with enabled keep_descriptor_pool_after_request
- See also UPB changes below, which may affect PHP C-Extension.

Ruby:
- [Ruby] Warn if assigning a "UTF-8" string with invalid UTF-8
- Remove Arena_pin in favor of adopting the UPB freezing API
- Fix Ruby FFI to pass MiniTable to upb_Message_New() aka new_message_from_def()

Ruby C-Extension:
- Move -Werror to our test/dev bazelrc files
- [Ruby] Warn if assigning a "UTF-8" string with invalid UTF-8
- [Ruby] Fix mismatched pointer type
- Remove Arena_pin in favor of adopting the UPB freezing API
- See also UPB changes below, which may affect Ruby C-Extension

UPB
- Move -Werror to our test/dev bazelrc files
- UPB text encoder without using reflection for Rust
- Fix delimited inheritance in all languages
- Fixed printing of nan floats/doubles in Python

Other:
- Remove --copt="-Werror" from .bazelrc
- Remove protobuf rust from BCR presubmits for now
- Set -ex in test_java.yml
- Refactor java maven GHA test to use our generated jars
- Remove /utf-8 flag added in #14197
- Downgrade CMake to 3.29 to workaround Abseil issue
- Add minimal Python support to MODULE.bazel
- Fix(bazel/python): incompatible_enable_proto_toolchain_resolution
- Add Rust support to MODULE.bazel
- Add rules_fuzzing dependency to MODULE.bazel
- Reenable FFI tests on CRuby
- Update comment for message_type
- Enable textproto conformance tests for "-0" and "-0F"
- Fix #10007: Propagate msvc-style link flags to clang-cl with Bazel
- Add system_python to protobuf_deps.bzl