diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index f32ff55..c4eab34 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -13,7 +13,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        java: [ 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 ]
+        java: [ 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 ]
     steps:
       - name: Checkout the repository
         uses: actions/checkout@v2
diff --git a/build.gradle b/build.gradle
index fef3a0b..147bdff 100644
--- a/build.gradle
+++ b/build.gradle
@@ -2,11 +2,11 @@ plugins {
   id 'jacoco'
   id 'java-library'
   id 'maven-publish'
-  id 'com.diffplug.spotless' version '6.10.0'
-  id 'com.github.ben-manes.versions' version '0.42.0'
-  id 'com.github.johnrengelman.shadow' version '7.1.2'
+  id 'com.diffplug.spotless' version '6.13.0'
+  id 'com.github.ben-manes.versions' version '0.50.0'
+  id 'com.github.johnrengelman.shadow' version '8.1.1'
   id 'net.researchgate.release' version '3.0.2'
-  id 'ru.vyarus.quality' version '4.8.0'
+  id 'ru.vyarus.quality' version '4.9.0'
 }
 
 group = 'com.github.tueda'
@@ -15,13 +15,13 @@ sourceCompatibility = '1.8'
 targetCompatibility = '1.8'
 
 def versions = [
-  checkstyle: '10.3.3',
-  junit: '5.9.0',
-  lombok: '1.18.24',
-  pmd: '6.49.0',
+  checkstyle: '10.12.6',
+  junit: '5.10.1',
+  lombok: '1.18.30',
+  pmd: '6.55.0',
   rings: '2.5.8',
-  spotbugs: '4.7.2',
-  truth: '1.1.3',
+  spotbugs: '4.8.3',
+  truth: '1.2.0',
 ]
 
 repositories {
@@ -90,6 +90,13 @@ configurations {
   checkstyleConfig
 }
 
+// See: https://github.com/google/guava/releases/tag/v32.1.0
+configurations.all {
+  resolutionStrategy.capabilitiesResolution.withCapability("com.google.collections:google-collections") {
+    select("com.google.guava:guava:0")
+  }
+}
+
 dependencies {
   checkstyleConfig("com.puppycrawl.tools:checkstyle:${versions.checkstyle}") {
     transitive = false
diff --git a/config/pmd.xml b/config/pmd.xml
index 13cd57a..1f6cee1 100644
--- a/config/pmd.xml
+++ b/config/pmd.xml
@@ -29,7 +29,6 @@
     <exclude name="CommentSize" />  <!-- Easily conflicts with Checkstyle -->
   </rule>
   <rule ref="category/java/errorprone.xml" >
-    <exclude name="BeanMembersShouldSerialize" />
     <exclude name="DataflowAnomalyAnalysis" />  <!-- Too many false positives -->
   </rule>
   <rule ref="category/java/errorprone.xml/AvoidLiteralsInIfCondition">
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
index 249e583..d64cd49 100644
Binary files a/gradle/wrapper/gradle-wrapper.jar and b/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index ae04661..1af9e09 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,5 +1,7 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-7.5.1-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.5-bin.zip
+networkTimeout=10000
+validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
diff --git a/gradlew b/gradlew
index a69d9cb..1aa94a4 100755
--- a/gradlew
+++ b/gradlew
@@ -55,7 +55,7 @@
 #       Darwin, MinGW, and NonStop.
 #
 #   (3) This script is generated from the Groovy template
-#       https://github.com/gradle/gradle/blob/master/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       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/.
@@ -80,13 +80,11 @@ do
     esac
 done
 
-APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
-
-APP_NAME="Gradle"
+# This is normally unused
+# shellcheck disable=SC2034
 APP_BASE_NAME=${0##*/}
-
-# 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"'
+# 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
@@ -133,22 +131,29 @@ location of your Java installation."
     fi
 else
     JAVACMD=java
-    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+    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 $MAX_FD"
     esac
@@ -193,11 +198,15 @@ if "$cygwin" || "$msys" ; then
     done
 fi
 
-# Collect all arguments for the java command;
-#   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
-#     shell script including quotes and variable substitutions, so put them in
-#     double quotes to make sure that they get re-expanded; and
-#   * put everything else in single quotes, so that it's not re-expanded.
+
+# 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" \
diff --git a/gradlew.bat b/gradlew.bat
index 53a6b23..6689b85 100644
--- a/gradlew.bat
+++ b/gradlew.bat
@@ -26,6 +26,7 @@ if "%OS%"=="Windows_NT" setlocal
 
 set DIRNAME=%~dp0
 if "%DIRNAME%"=="" set DIRNAME=.
+@rem This is normally unused
 set APP_BASE_NAME=%~n0
 set APP_HOME=%DIRNAME%