diff --git a/README.adoc b/README.adoc
deleted file mode 100644
index a42662c..0000000
--- a/README.adoc
+++ /dev/null
@@ -1,14 +0,0 @@
-# xbib Time
-
-image:https://api.travis-ci.org/xbib/time.svg[title="Build status", link="https://travis-ci.org/xbib/time/"]
-image:https://img.shields.io/sonar/http/nemo.sonarqube.com/org.xbib%3Atime/coverage.svg?style=flat-square[title="Coverage", link="https://sonarqube.com/dashboard/index?id=org.xbib%3Atime"]
-image:https://maven-badges.herokuapp.com/maven-central/org.xbib/time/badge.svg[title="Maven Central", link="http://search.maven.org/#search%7Cga%7C1%7Cxbib%20time"]
-image:https://img.shields.io/badge/License-Apache%202.0-blue.svg[title="Apache License 2.0", link="https://opensource.org/licenses/Apache-2.0"]
-
-This is a bundle of time utilities for Java 8 Time API. It consists of
-
-- Chronic: parsing natural language to compute time spans (from https://github.com/samtingleff/jchronic)
-- Pretty: pretty printing time durations (from https://github.com/ocpsoft/prettytime)
-- Format: format time descriptions (from https://github.com/JodaOrg/joda-time)
-
-This project has no dependencies.
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..96cce36
--- /dev/null
+++ b/README.md
@@ -0,0 +1,9 @@
+# xbib Time
+
+This is a bundle of time utilities for Java 8 Time API. It consists of
+
+- Chronic: parsing natural language to compute time spans (from https://github.com/samtingleff/jchronic)
+- Pretty: pretty printing time durations (from https://github.com/ocpsoft/prettytime)
+- Format: format time descriptions (from https://github.com/JodaOrg/joda-time)
+
+This project has no dependencies.
diff --git a/build.gradle b/build.gradle
index c750a0b..94a38a5 100644
--- a/build.gradle
+++ b/build.gradle
@@ -4,7 +4,7 @@ plugins {
 }
 
 wrapper {
-    gradleVersion = "${project.property('gradle.wrapper.version')}"
+    gradleVersion = libs.versions.gradle.get()
     distributionType = Wrapper.DistributionType.ALL
 }
 
@@ -25,14 +25,15 @@ ext {
 
 apply plugin: 'java-library'
 
-dependencies {
-    testImplementation "org.quartz-scheduler:quartz:${project.property('quartz.version')}"
-    testImplementation "com.google.caliper:caliper:${project.property('caliper.version')}"
-}
-
 apply from: rootProject.file('gradle/ide/idea.gradle')
 apply from: rootProject.file('gradle/repositories/maven.gradle')
 apply from: rootProject.file('gradle/compile/java.gradle')
 apply from: rootProject.file('gradle/test/junit5.gradle')
 apply from: rootProject.file('gradle/publishing/publication.gradle')
 apply from: rootProject.file('gradle/publishing/sonatype.gradle')
+
+dependencies {
+    testImplementation libs.quartz
+    testImplementation libs.caliper
+}
+
diff --git a/gradle.properties b/gradle.properties
index 04a120c..6d58ced 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -1,8 +1,5 @@
 group = org.xbib
 name = time
-version = 2.2.0
+version = 2.3.0
 
 org.gradle.warning.mode = ALL
-gradle.wrapper.version = 7.3.2
-quartz.version = 2.3.2
-caliper.version = 1.0-beta-2
diff --git a/gradle/test/junit5.gradle b/gradle/test/junit5.gradle
index d08c379..09ce233 100644
--- a/gradle/test/junit5.gradle
+++ b/gradle/test/junit5.gradle
@@ -1,12 +1,8 @@
-
-def junitVersion = project.hasProperty('junit.version')?project.property('junit.version'):'5.8.2'
-def hamcrestVersion = project.hasProperty('hamcrest.version')?project.property('hamcrest.version'):'2.2'
-
 dependencies {
-    testImplementation "org.junit.jupiter:junit-jupiter-api:${junitVersion}"
-    testImplementation "org.junit.jupiter:junit-jupiter-params:${junitVersion}"
-    testImplementation "org.hamcrest:hamcrest-library:${hamcrestVersion}"
-    testRuntimeOnly "org.junit.jupiter:junit-jupiter-engine:${junitVersion}"
+    testImplementation libs.junit.jupiter.api
+    testImplementation libs.junit.jupiter.params
+    testImplementation libs.hamcrest
+    testRuntimeOnly libs.junit.jupiter.engine
 }
 
 test {
@@ -24,4 +20,16 @@ test {
                     "${result.skippedTestCount} skipped"
         }
     }
+    // for Guava using reflection on JDK classes which JDK17 does not like
+    jvmArgs '--add-exports=java.base/jdk.internal.misc=ALL-UNNAMED',
+            '--add-exports=java.base/jdk.internal.ref=ALL-UNNAMED',
+            '--add-exports=java.base/sun.nio.ch=ALL-UNNAMED',
+            '--add-exports=jdk.unsupported/sun.misc=ALL-UNNAMED',
+            '--add-exports=jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED',
+            '--add-opens=jdk.compiler/com.sun.tools.javac=ALL-UNNAMED',
+            '--add-opens=java.base/java.lang=ALL-UNNAMED',
+            '--add-opens=java.base/java.lang.reflect=ALL-UNNAMED',
+            '--add-opens=java.base/java.io=ALL-UNNAMED',
+            '--add-opens=java.base/java.util=ALL-UNNAMED'
+
 }
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
index 7454180..249e583 100644
Binary files a/gradle/wrapper/gradle-wrapper.jar and b/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index ac0b842..2ec77e5 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-7.3.2-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.5-all.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
diff --git a/gradlew b/gradlew
index 1b6c787..a69d9cb 100755
--- a/gradlew
+++ b/gradlew
@@ -205,6 +205,12 @@ set -- \
         org.gradle.wrapper.GradleWrapperMain \
         "$@"
 
+# 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.
diff --git a/gradlew.bat b/gradlew.bat
index ac1b06f..53a6b23 100644
--- a/gradlew.bat
+++ b/gradlew.bat
@@ -14,7 +14,7 @@
 @rem limitations under the License.
 @rem
 
-@if "%DEBUG%" == "" @echo off
+@if "%DEBUG%"=="" @echo off
 @rem ##########################################################################
 @rem
 @rem  Gradle startup script for Windows
@@ -25,7 +25,7 @@
 if "%OS%"=="Windows_NT" setlocal
 
 set DIRNAME=%~dp0
-if "%DIRNAME%" == "" set DIRNAME=.
+if "%DIRNAME%"=="" set DIRNAME=.
 set APP_BASE_NAME=%~n0
 set APP_HOME=%DIRNAME%
 
@@ -40,7 +40,7 @@ if defined JAVA_HOME goto findJavaFromJavaHome
 
 set JAVA_EXE=java.exe
 %JAVA_EXE% -version >NUL 2>&1
-if "%ERRORLEVEL%" == "0" goto execute
+if %ERRORLEVEL% equ 0 goto execute
 
 echo.
 echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
@@ -75,13 +75,15 @@ set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
 
 :end
 @rem End local scope for the variables with windows NT shell
-if "%ERRORLEVEL%"=="0" goto mainEnd
+if %ERRORLEVEL% equ 0 goto mainEnd
 
 :fail
 rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
 rem the _cmd.exe /c_ return code!
-if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
-exit /b 1
+set EXIT_CODE=%ERRORLEVEL%
+if %EXIT_CODE% equ 0 set EXIT_CODE=1
+if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE%
+exit /b %EXIT_CODE%
 
 :mainEnd
 if "%OS%"=="Windows_NT" endlocal
diff --git a/settings.gradle b/settings.gradle
index 89f4110..b14355c 100644
--- a/settings.gradle
+++ b/settings.gradle
@@ -1 +1,16 @@
-rootProject.name = name
+dependencyResolutionManagement {
+    versionCatalogs {
+        libs {
+            version('gradle', '7.5')
+            version('groovy', '3.0.10')
+            version('junit', '5.8.2')
+            library('junit-jupiter-api', 'org.junit.jupiter', 'junit-jupiter-api').versionRef('junit')
+            library('junit-jupiter-params', 'org.junit.jupiter', 'junit-jupiter-params').versionRef('junit')
+            library('junit-jupiter-engine', 'org.junit.jupiter', 'junit-jupiter-engine').versionRef('junit')
+            library('hamcrest', 'org.hamcrest', 'hamcrest-library').version('2.2')
+            library('junit4', 'junit', 'junit').version('4.13.2')
+            library('quartz', 'org.quartz-scheduler', 'quartz').version('2.3.2')
+            library('caliper',  'com.google.caliper', 'caliper').version('1.0-beta-3')
+        }
+    }
+}
diff --git a/src/main/java/module-info.java b/src/main/java/module-info.java
index aff965b..9b1a76e 100644
--- a/src/main/java/module-info.java
+++ b/src/main/java/module-info.java
@@ -9,5 +9,4 @@ module org.xbib.time {
     exports org.xbib.time.pretty.i18n;
     exports org.xbib.time.pretty.units;
     exports org.xbib.time.schedule;
-    exports org.xbib.time.util;
 }
diff --git a/src/main/java/org/xbib/time/schedule/DayOfWeekField.java b/src/main/java/org/xbib/time/schedule/DayOfWeekField.java
index 9ebaa42..038165c 100644
--- a/src/main/java/org/xbib/time/schedule/DayOfWeekField.java
+++ b/src/main/java/org/xbib/time/schedule/DayOfWeekField.java
@@ -117,8 +117,8 @@ public class DayOfWeekField extends DefaultField {
         protected Builder(boolean oneBased) {
             super(1, 7);
             this.oneBased = oneBased;
-            last = new LinkedHashSet<>();
-            nth = new LinkedHashSetMultiMap<>();
+            this.last = new LinkedHashSet<>();
+            this.nth = new LinkedHashSetMultiMap<>();
         }
 
         @Override
diff --git a/src/test/java/org/xbib/time/pretty/PrettyTimeI18n_in_ID_Test.java b/src/test/java/org/xbib/time/pretty/PrettyTimeI18n_in_ID_Test.java
index f190551..54d2301 100644
--- a/src/test/java/org/xbib/time/pretty/PrettyTimeI18n_in_ID_Test.java
+++ b/src/test/java/org/xbib/time/pretty/PrettyTimeI18n_in_ID_Test.java
@@ -26,9 +26,9 @@ public class PrettyTimeI18n_in_ID_Test {
 
     @Test
     public void testLocaleISOCorrectness() {
-        assertEquals("in", this.locale.getLanguage());
+        assertEquals("id", this.locale.getLanguage());
         assertEquals("ID", this.locale.getCountry());
-        assertEquals("Bahasa Indonesia", this.locale.getDisplayLanguage());
+        assertEquals("Indonesia", this.locale.getDisplayLanguage());
         assertEquals("Indonesia", this.locale.getDisplayCountry());
     }