Convert to Gradle.

This commit converts the project from Maven to Gradle by removing the
old Maven-related files such as `pom.xml` and the Maven Wrapper, and
replacing them with their Gradle counterparts (more or less).

Comparing the artifacts from Maven and Gradle indicates no significant
differences in the resulting jar-files, and a quick test of the plugin
shows that things are still working as expected.

Bits of `build.gradle.kts` may need a bit of a tune-up later down the
road, e.g. the test sources "hack" put in place. It may be cleaner to
omit this hack and just suck up having to repeat dependencies, but in
that case, it might be better to embrace the "libs" file instead of
having to repeat dependencies in full.

Note that this commit changes the caching mechanism used in the GitHub
Actions build workflow, opting for the one built into `setup-java`.

.github/workflows/build.yml

@@ -17,19 +17,13 @@ jobs:
         with:
           java-version: '11'
           distribution: 'adopt'
-
-      - name: 'Cache dependencies'
-        uses: actions/cache@v3
-        with:
-          path: ~/.m2
-          key: ${{ runner.os }}-m2-${{ hashFiles('**/pom.xml') }}
-          restore-keys: ${{ runner.os }}-m2
+          cache: 'gradle'
 
       - name: 'Build, test, and package'
-        run: mvn -B package --file pom.xml
+        run: ./gradlew build --no-daemon
 
       - name: 'Upload artifact'
         uses: actions/upload-artifact@v3
         with:
           name: MobArena.jar
-          path: target/MobArena.jar
+          path: build/libs/MobArena.jar

.gitignore

@@ -1,12 +1,9 @@
 # Java
 *.class
 
-# Maven
-target/
-
-# Artifacts
-*.jar
-*.zip
+# Gradle
+.gradle/
+build/
 
 # IntelliJ
 .idea/

build.gradle.kts

@@ -0,0 +1,69 @@
+plugins {
+    id("java-library")
+    id("com.github.johnrengelman.shadow") version "8.1.1"
+}
+
+group = "com.garbagemule"
+version = "0.107.1-SNAPSHOT"
+
+repositories {
+    mavenLocal()
+    maven("https://hub.spigotmc.org/nexus/content/repositories/snapshots/")
+    maven("https://jitpack.io")
+    maven("https://repo.maven.apache.org/maven2/")
+}
+
+dependencies {
+    compileOnly("org.spigotmc:spigot-api:1.19-R0.1-SNAPSHOT")
+    compileOnly("com.github.MilkBowl:VaultAPI:1.7.1")
+    api("org.bstats:bstats-bukkit:2.2.1")
+
+    testImplementation("junit:junit:4.13.2")
+    testImplementation("org.hamcrest:hamcrest-all:1.3")
+    testImplementation("org.mockito:mockito-core:3.12.4")
+}
+
+java {
+    toolchain {
+        languageVersion.set(JavaLanguageVersion.of(8))
+    }
+}
+
+sourceSets {
+    test {
+        // This is a bit of a hack. It ensures that the dependencies for the
+        // "main" source set are available to the test suite. Without it, the
+        // dependencies would have to be listed twice, and even that doesn't
+        // seem to work with the currently used version of Mockito.
+        configurations.testImplementation.configure {
+            extendsFrom(configurations.compileOnly.get())
+        }
+    }
+}
+
+tasks {
+    processResources {
+        filesMatching("plugin.yml") {
+            expand("project" to mapOf(
+                "name" to "MobArena",
+                "version" to version,
+            ))
+        }
+    }
+
+    shadowJar {
+        minimize()
+
+        relocate("org.bstats", "com.garbagemule.MobArena.metrics")
+
+        archiveBaseName = "MobArena"
+        archiveClassifier = ""
+        archiveVersion = ""
+    }
+
+    // We're using shadowJar, so we can skip the regular jar task.
+    jar { enabled = false }
+
+    // Let the build task produce the final artifact.
+    build { dependsOn(shadowJar) }
+}

gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,7 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.5-bin.zip
+networkTimeout=10000
+validateDistributionUrl=true
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

gradlew

@@ -0,0 +1,249 @@
+#!/bin/sh
+
+#
+# Copyright © 2015-2021 the original authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+##############################################################################
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/HEAD/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
+##############################################################################
+
+# Attempt to set APP_HOME
+
+# Resolve links: $0 may be a link
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+    [ -h "$app_path" ]
+do
+    ls=$( ls -ld "$app_path" )
+    link=${ls#*' -> '}
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
+done
+
+# This is normally unused
+# shellcheck disable=SC2034
+APP_BASE_NAME=${0##*/}
+# Discard cd standard output in case $CDPATH is set (https://github.com/gradle/gradle/issues/25036)
+APP_HOME=$( cd "${APP_HOME:-./}" > /dev/null && pwd -P ) || exit
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD=maximum
+
+warn () {
+    echo "$*"
+} >&2
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+} >&2
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | MINGW* )  msys=true    ;; #(
+  NONSTOP* )        nonstop=true ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD=$JAVA_HOME/jre/sh/java
+    else
+        JAVACMD=$JAVA_HOME/bin/java
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD=java
+    if ! command -v java >/dev/null 2>&1
+    then
+        die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+fi
+
+# Increase the maximum file descriptors if we can.
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
+        ulimit -n "$MAX_FD" ||
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
+    esac
+fi
+
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
+        fi
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
+    done
+fi
+
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Collect all arguments for the java command:
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,
+#     and any embedded shellness will be escaped.
+#   * For example: A user cannot expect ${Hostname} to be expanded, as it is an environment variable and will be
+#     treated as '${Hostname}' itself on the command line.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        org.gradle.wrapper.GradleWrapperMain \
+        "$@"
+
+# Stop when "xargs" is not available.
+if ! command -v xargs >/dev/null 2>&1
+then
+    die "xargs is not available"
+fi
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
+
+exec "$JAVACMD" "$@"