[Mohit (mohitc1)]

Bumps Kotlin from 1.8.0 to 2.0.21, with languageVersion/apiVersion pinned to 1.9 on every module that publishes a consumable artifact.

Why

Kotlin 1.8 cannot read dependency metadata stamped by a Kotlin 2.0 compiler, which forces -Xskip-metadata-version-check onto any module consuming a modern dependency. That flag is module-wide, so it silently disables the check for every dependency, not just the intended one. This removes the need for it.

How it works

• The 2.0.21 compiler reads dependency metadata up to Kotlin 2.1, so no skip flag is required.
• languageVersion/apiVersion = 1.9 keeps the K1 frontend, so this is not a K2 migration — no smart-cast/inference/Lombok-interop fallout.
• Emitted metadata is therefore version 1.9.0, which consumers still on Kotlin 1.8 can read. No downstream break for MSAL customers, OneAuth, Teams or Outlook.

Verified by inspecting the compiled output: kotlin.Metadata(mv=[1,9,0]).

Validation

• :common:compileLocalDebugKotlin — BUILD SUCCESSFUL
• :common:compileLocalDebugUnitTestKotlin — BUILD SUCCESSFUL
• :common:testLocalDebugUnitTest — 1925 tests, 1786 passed. The 139 failures are all pre-existing and environmental: the nativeauth.integration suites require the pipeline-supplied MOCK_API_URL, which is empty on a dev box, and one PackageUtilsTest failure is Mockito state bleed from SignUpOAuth2StrategyTest.setup in the same worker JVM.

Notes for reviewers

• Test apps and mock apps are deliberately not pinned — nothing consumes their metadata. They will compile under K2, so they are the most likely place to see new errors.
• common/testutils is pinned: it is maven-publish + kotlin-android, so it emits metadata consumed by the broker/msal/adal automation suites.
• This also aligns the monorepo with the Authenticator app, which is already on Kotlin 2.0.21 and was previously the de-facto source of truth for the Compose/KSP plugin versions while kotlinVersion said 1.8.0.

Work item

• AB#3742062 - Bump Kotlin to 2.0.21 across common, broker, msal, adal and android-complete

assistance: agentic-ide
type: chore
agent-tool: copilot-chat
agent-model: claude-opus-4.5
work-item: AB#3742062