[perNyfelt]

Combined-only roots currently need a second plugin ID to avoid registering single-publication release tasks. Consolidate that workflow into se.alipsa.nexus-release-plugin through nexusReleasePlugin { combinedRelease { } }, with shared path, credential and endpoint conventions. The root-only nexusReleasePlugin.rootSinglePublicationTasks=false property preserves unqualified subproject bundle/release selectors and custom root tasks; existing single-publication behavior remains the default.

Shared properties are created before task registration, so eager convention rules work. The registrar is constructor-supplied and private, and combined task providers are read-only. Remove the separate plugin declaration/marker and ReleaseAllSupportPlugin class, document Groovy/Kotlin migration and unchanged timeout behavior, and set the development version to 2.4.0-SNAPSHOT.

Validation:

• Full build with -PrequireShellHarness=true, including charset and shell checks.
• Gradle 8.13 / 9.8.1 × JDK 17 / 21: 56 selected tests passed per cell, no skips. CI now includes the combined DSL, integration and root-selector fixtures.
• Strict configuration-cache reuse for combined tasks and subproject release selectors; changing the root opt-out invalidates the cache. Status-only resume schedules only releaseAll.
• JAR and publication inspection confirms one plugin descriptor, the original implementation coordinates and marker, and no retired class.
• publishPlugins --validate-only -Pversion=2.4.0 passed without upload. The version override is required because the Portal rejects SNAPSHOT validation.

See req/verification/v2.4.0-single-plugin.md for the commands and results. Matrix's external build and guide need the documented consumer migration separately; no external repository or real Portal deployment was changed.