Go back to single-root-module layout

This is a single-module project anyway, and keeping layout with single
submodule caused some issues.

Author: damianmalczewski

.github/copilot-instructions.md

@@ -8,8 +8,6 @@
   libraries/applications.
 - **Languages:** Java (main), Kotlin (build scripts).
 - **Frameworks/Tools:** Gradle (Kotlin DSL), JUnit Jupiter, AssertJ, Spotless, GitHub Actions CI.
-- **Modules:**
-  - `problem4j-core` - core module of Problem4J set of libraries.
 - **Java Version:** Java 8+ (toolchain set to 8, CI builds/tests on JDK 17 due to Gradle 9+ runtime requirements).
 - **Repo Size:** Small (core source, tests, build scripts, CI/CD workflows).
 
@@ -41,12 +39,10 @@
 
 - **Root Files:** `build.gradle.kts`, `settings.gradle.kts`, `README.md`, `RELEASING.md`, `gradlew`, `gradlew.bat`,
   `gradle/libs.versions.toml`, `.github/workflows/`.
-- **Source Code:** `src/main/java` in each module.
-- **Tests:** `src/test/java` in each module.
+- **Source Code:** `src/main/java`.
+- **Tests:** `src/test/java`.
 - **Build Scripts:** All modules have `build.gradle.kts`.
 - **Build Utils:** Custom Gradle scripts in `buildSrc`.
-- **Module Directories:**
-  - `problem4j-core`: Problem4J core, framework-agnostic module.
 
 ## Coding Guidelines
 

.github/workflows/gradle-publish-release.yml

@@ -41,4 +41,4 @@ jobs:
         run: |
           VERSION="${GITHUB_REF_NAME#v}"  # removes leading 'v' from tag name
           echo "::notice::publishing version $VERSION"
-          ./gradlew -Pversion="$VERSION" -Psign publishAggregationToCentralPortal
+          ./gradlew -Pversion="$VERSION" -Psign publishAllPublicationsToCentralPortal

build.gradle.kts

@@ -1,18 +1,28 @@
 import com.diffplug.spotless.LineEnding
 
 plugins {
-    id("internal.convention-common")
-    alias(libs.plugins.nmcp).apply(false)
-    alias(libs.plugins.nmcp.aggregation)
+    id("internal.convention-java-library")
+    id("internal.convention-publishing")
+    alias(libs.plugins.nmcp)
     alias(libs.plugins.spotless)
 }
 
+internalPublishing {
+    displayName = "Problem4J Core"
+    description = "Core library implementing Problem model according to RFC7807 (aka RFC9457)."
+}
+
 dependencies {
-    nmcpAggregation(project(":problem4j-core"))
+    testImplementation(platform(libs.junit.bom))
+
+    testImplementation(libs.junit.jupiter)
+    testRuntimeOnly(libs.junit.platform.launcher)
+
+    testImplementation(libs.assertj.core)
 }
 
-nmcpAggregation {
-    centralPortal {
+nmcp {
+    publishAllPublicationsToCentralPortal {
         username = System.getenv("PUBLISHING_USERNAME")
         password = System.getenv("PUBLISHING_PASSWORD")
 
@@ -40,7 +50,7 @@ spotless {
     }
 
     kotlinGradle {
-        target("*.gradle.kts", "problem4j-*/*.gradle.kts", "buildSrc/*.gradle.kts", "buildSrc/src/**/*.gradle.kts")
+        target("*.gradle.kts", "buildSrc/*.gradle.kts", "buildSrc/src/**/*.gradle.kts")
 
         ktlint("1.8.0").editorConfigOverride(mapOf("max_line_length" to "120"))
         endWithNewline()

gradle/libs.versions.toml

@@ -6,7 +6,6 @@ spotless = "8.1.0"
 
 [plugins]
 nmcp = { id = "com.gradleup.nmcp", version.ref = "nmcp" }
-nmcp-aggregation = { id = "com.gradleup.nmcp.aggregation", version.ref = "nmcp" }
 spotless = { id = "com.diffplug.spotless", version.ref = "spotless" }
 
 [libraries]

problem4j-core/build.gradle.kts

@@ -8,8 +8,4 @@ plugins {
     id("org.gradle.toolchains.foojay-resolver-convention").version("1.0.0")
 }
 
-// If rootProject.name matches project.name, it fails to generate output for nmcpZipAggregation task - two modules must
-// not have the same name (with root included). That's the reason for rootProject.name not matching repository name.
-rootProject.name = "problem4j-core-root"
-
-include(":problem4j-core")
+rootProject.name = "problem4j-core"