diff --git a/build.gradle b/build.gradle
index cb92561..5e5d5e9 100644
--- a/build.gradle
+++ b/build.gradle
@@ -7,7 +7,7 @@ buildscript {
 plugins {
     id 'java-library'
     id 'jacoco'
-    id 'com.github.kt3k.coveralls' version '2.8.2'
+    id 'com.github.kt3k.coveralls' version '2.10.1'
 }
 
 group = "de.bwaldvogel"
@@ -46,7 +46,7 @@ jacocoTestReport {
 }
 
 wrapper {
-    gradleVersion = "5.5.1"
+    gradleVersion = "6.7.1"
     distributionType = Wrapper.DistributionType.ALL
 }
 
diff --git a/gradle.lockfile b/gradle.lockfile
new file mode 100644
index 0000000..b8dba1e
--- /dev/null
+++ b/gradle.lockfile
@@ -0,0 +1,18 @@
+# This is a Gradle generated file for dependency locking.
+# Manual edits can break the build and are not advised.
+# This file is expected to be part of source control.
+ch.qos.logback:logback-classic:1.2.3=testRuntimeClasspath
+ch.qos.logback:logback-core:1.2.3=testRuntimeClasspath
+junit:junit:4.13.1=testCompileClasspath,testRuntimeClasspath
+org.assertj:assertj-core:3.18.1=testCompileClasspath,testRuntimeClasspath
+org.hamcrest:hamcrest-core:1.3=testCompileClasspath,testRuntimeClasspath
+org.jacoco:org.jacoco.agent:0.8.5=jacocoAgent,jacocoAnt
+org.jacoco:org.jacoco.ant:0.8.5=jacocoAnt
+org.jacoco:org.jacoco.core:0.8.5=jacocoAnt
+org.jacoco:org.jacoco.report:0.8.5=jacocoAnt
+org.ow2.asm:asm-analysis:7.2=jacocoAnt
+org.ow2.asm:asm-commons:7.2=jacocoAnt
+org.ow2.asm:asm-tree:7.2=jacocoAnt
+org.ow2.asm:asm:7.2=jacocoAnt
+org.slf4j:slf4j-api:1.7.30=testCompileClasspath,testRuntimeClasspath
+empty=annotationProcessor,compileClasspath,runtimeClasspath,testAnnotationProcessor
diff --git a/gradle/dependency-locks/annotationProcessor.lockfile b/gradle/dependency-locks/annotationProcessor.lockfile
deleted file mode 100644
index 656c5db..0000000
--- a/gradle/dependency-locks/annotationProcessor.lockfile
+++ /dev/null
@@ -1,3 +0,0 @@
-# This is a Gradle generated file for dependency locking.
-# Manual edits can break the build and are not advised.
-# This file is expected to be part of source control.
diff --git a/gradle/dependency-locks/archives.lockfile b/gradle/dependency-locks/archives.lockfile
deleted file mode 100644
index 656c5db..0000000
--- a/gradle/dependency-locks/archives.lockfile
+++ /dev/null
@@ -1,3 +0,0 @@
-# This is a Gradle generated file for dependency locking.
-# Manual edits can break the build and are not advised.
-# This file is expected to be part of source control.
diff --git a/gradle/dependency-locks/compile.lockfile b/gradle/dependency-locks/compile.lockfile
deleted file mode 100644
index 656c5db..0000000
--- a/gradle/dependency-locks/compile.lockfile
+++ /dev/null
@@ -1,3 +0,0 @@
-# This is a Gradle generated file for dependency locking.
-# Manual edits can break the build and are not advised.
-# This file is expected to be part of source control.
diff --git a/gradle/dependency-locks/compileClasspath.lockfile b/gradle/dependency-locks/compileClasspath.lockfile
deleted file mode 100644
index 656c5db..0000000
--- a/gradle/dependency-locks/compileClasspath.lockfile
+++ /dev/null
@@ -1,3 +0,0 @@
-# This is a Gradle generated file for dependency locking.
-# Manual edits can break the build and are not advised.
-# This file is expected to be part of source control.
diff --git a/gradle/dependency-locks/compileOnly.lockfile b/gradle/dependency-locks/compileOnly.lockfile
deleted file mode 100644
index 656c5db..0000000
--- a/gradle/dependency-locks/compileOnly.lockfile
+++ /dev/null
@@ -1,3 +0,0 @@
-# This is a Gradle generated file for dependency locking.
-# Manual edits can break the build and are not advised.
-# This file is expected to be part of source control.
diff --git a/gradle/dependency-locks/default.lockfile b/gradle/dependency-locks/default.lockfile
deleted file mode 100644
index 656c5db..0000000
--- a/gradle/dependency-locks/default.lockfile
+++ /dev/null
@@ -1,3 +0,0 @@
-# This is a Gradle generated file for dependency locking.
-# Manual edits can break the build and are not advised.
-# This file is expected to be part of source control.
diff --git a/gradle/dependency-locks/jacocoAgent.lockfile b/gradle/dependency-locks/jacocoAgent.lockfile
deleted file mode 100644
index e22f361..0000000
--- a/gradle/dependency-locks/jacocoAgent.lockfile
+++ /dev/null
@@ -1,4 +0,0 @@
-# This is a Gradle generated file for dependency locking.
-# Manual edits can break the build and are not advised.
-# This file is expected to be part of source control.
-org.jacoco:org.jacoco.agent:0.8.4
diff --git a/gradle/dependency-locks/jacocoAnt.lockfile b/gradle/dependency-locks/jacocoAnt.lockfile
deleted file mode 100644
index 9a2c3a0..0000000
--- a/gradle/dependency-locks/jacocoAnt.lockfile
+++ /dev/null
@@ -1,11 +0,0 @@
-# This is a Gradle generated file for dependency locking.
-# Manual edits can break the build and are not advised.
-# This file is expected to be part of source control.
-org.jacoco:org.jacoco.agent:0.8.4
-org.jacoco:org.jacoco.ant:0.8.4
-org.jacoco:org.jacoco.core:0.8.4
-org.jacoco:org.jacoco.report:0.8.4
-org.ow2.asm:asm-analysis:7.1
-org.ow2.asm:asm-commons:7.1
-org.ow2.asm:asm-tree:7.1
-org.ow2.asm:asm:7.1
diff --git a/gradle/dependency-locks/runtime.lockfile b/gradle/dependency-locks/runtime.lockfile
deleted file mode 100644
index 656c5db..0000000
--- a/gradle/dependency-locks/runtime.lockfile
+++ /dev/null
@@ -1,3 +0,0 @@
-# This is a Gradle generated file for dependency locking.
-# Manual edits can break the build and are not advised.
-# This file is expected to be part of source control.
diff --git a/gradle/dependency-locks/runtimeClasspath.lockfile b/gradle/dependency-locks/runtimeClasspath.lockfile
deleted file mode 100644
index 656c5db..0000000
--- a/gradle/dependency-locks/runtimeClasspath.lockfile
+++ /dev/null
@@ -1,3 +0,0 @@
-# This is a Gradle generated file for dependency locking.
-# Manual edits can break the build and are not advised.
-# This file is expected to be part of source control.
diff --git a/gradle/dependency-locks/testAnnotationProcessor.lockfile b/gradle/dependency-locks/testAnnotationProcessor.lockfile
deleted file mode 100644
index 656c5db..0000000
--- a/gradle/dependency-locks/testAnnotationProcessor.lockfile
+++ /dev/null
@@ -1,3 +0,0 @@
-# This is a Gradle generated file for dependency locking.
-# Manual edits can break the build and are not advised.
-# This file is expected to be part of source control.
diff --git a/gradle/dependency-locks/testCompile.lockfile b/gradle/dependency-locks/testCompile.lockfile
deleted file mode 100644
index 656c5db..0000000
--- a/gradle/dependency-locks/testCompile.lockfile
+++ /dev/null
@@ -1,3 +0,0 @@
-# This is a Gradle generated file for dependency locking.
-# Manual edits can break the build and are not advised.
-# This file is expected to be part of source control.
diff --git a/gradle/dependency-locks/testCompileClasspath.lockfile b/gradle/dependency-locks/testCompileClasspath.lockfile
deleted file mode 100644
index 9ea06eb..0000000
--- a/gradle/dependency-locks/testCompileClasspath.lockfile
+++ /dev/null
@@ -1,7 +0,0 @@
-# This is a Gradle generated file for dependency locking.
-# Manual edits can break the build and are not advised.
-# This file is expected to be part of source control.
-junit:junit:4.12
-org.assertj:assertj-core:3.13.2
-org.hamcrest:hamcrest-core:1.3
-org.slf4j:slf4j-api:1.7.26
diff --git a/gradle/dependency-locks/testCompileOnly.lockfile b/gradle/dependency-locks/testCompileOnly.lockfile
deleted file mode 100644
index 656c5db..0000000
--- a/gradle/dependency-locks/testCompileOnly.lockfile
+++ /dev/null
@@ -1,3 +0,0 @@
-# This is a Gradle generated file for dependency locking.
-# Manual edits can break the build and are not advised.
-# This file is expected to be part of source control.
diff --git a/gradle/dependency-locks/testRuntime.lockfile b/gradle/dependency-locks/testRuntime.lockfile
deleted file mode 100644
index 656c5db..0000000
--- a/gradle/dependency-locks/testRuntime.lockfile
+++ /dev/null
@@ -1,3 +0,0 @@
-# This is a Gradle generated file for dependency locking.
-# Manual edits can break the build and are not advised.
-# This file is expected to be part of source control.
diff --git a/gradle/dependency-locks/testRuntimeClasspath.lockfile b/gradle/dependency-locks/testRuntimeClasspath.lockfile
deleted file mode 100644
index 8ca954c..0000000
--- a/gradle/dependency-locks/testRuntimeClasspath.lockfile
+++ /dev/null
@@ -1,9 +0,0 @@
-# This is a Gradle generated file for dependency locking.
-# Manual edits can break the build and are not advised.
-# This file is expected to be part of source control.
-ch.qos.logback:logback-classic:1.2.3
-ch.qos.logback:logback-core:1.2.3
-junit:junit:4.12
-org.assertj:assertj-core:3.13.2
-org.hamcrest:hamcrest-core:1.3
-org.slf4j:slf4j-api:1.7.26
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
index 5c2d1cf..e708b1c 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 430dfab..1f3fdbc 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-5.5.1-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.7.1-all.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
diff --git a/gradlew b/gradlew
index 8e25e6c..4f906e0 100755
--- a/gradlew
+++ b/gradlew
@@ -82,6 +82,7 @@ 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
@@ -125,10 +126,11 @@ if $darwin; then
     GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
 fi
 
-# For Cygwin, switch paths to Windows format before running java
-if $cygwin ; then
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if [ "$cygwin" = "true" -o "$msys" = "true" ] ; then
     APP_HOME=`cygpath --path --mixed "$APP_HOME"`
     CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
+
     JAVACMD=`cygpath --unix "$JAVACMD"`
 
     # We build the pattern for arguments to be converted via cygpath
@@ -154,19 +156,19 @@ if $cygwin ; then
         else
             eval `echo args$i`="\"$arg\""
         fi
-        i=$((i+1))
+        i=`expr $i + 1`
     done
     case $i in
-        (0) set -- ;;
-        (1) set -- "$args0" ;;
-        (2) set -- "$args0" "$args1" ;;
-        (3) set -- "$args0" "$args1" "$args2" ;;
-        (4) set -- "$args0" "$args1" "$args2" "$args3" ;;
-        (5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
-        (6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
-        (7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
-        (8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
-        (9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+        0) set -- ;;
+        1) set -- "$args0" ;;
+        2) set -- "$args0" "$args1" ;;
+        3) set -- "$args0" "$args1" "$args2" ;;
+        4) set -- "$args0" "$args1" "$args2" "$args3" ;;
+        5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
+        6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
+        7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
+        8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
+        9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
     esac
 fi
 
@@ -175,14 +177,9 @@ save () {
     for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
     echo " "
 }
-APP_ARGS=$(save "$@")
+APP_ARGS=`save "$@"`
 
 # Collect all arguments for the java command, following the shell quoting and substitution rules
 eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
 
-# by default we should be in the correct project dir, but when run from Finder on Mac, the cwd is wrong
-if [ "$(uname)" = "Darwin" ] && [ "$HOME" = "$PWD" ]; then
-  cd "$(dirname "$0")"
-fi
-
 exec "$JAVACMD" "$@"
diff --git a/gradlew.bat b/gradlew.bat
index 24467a1..ac1b06f 100644
--- a/gradlew.bat
+++ b/gradlew.bat
@@ -29,6 +29,9 @@ if "%DIRNAME%" == "" set DIRNAME=.
 set APP_BASE_NAME=%~n0
 set APP_HOME=%DIRNAME%
 
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
 @rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
 set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
 
@@ -37,7 +40,7 @@ if defined JAVA_HOME goto findJavaFromJavaHome
 
 set JAVA_EXE=java.exe
 %JAVA_EXE% -version >NUL 2>&1
-if "%ERRORLEVEL%" == "0" goto init
+if "%ERRORLEVEL%" == "0" goto execute
 
 echo.
 echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
@@ -51,7 +54,7 @@ goto fail
 set JAVA_HOME=%JAVA_HOME:"=%
 set JAVA_EXE=%JAVA_HOME%/bin/java.exe
 
-if exist "%JAVA_EXE%" goto init
+if exist "%JAVA_EXE%" goto execute
 
 echo.
 echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
@@ -61,28 +64,14 @@ echo location of your Java installation.
 
 goto fail
 
-:init
-@rem Get command-line arguments, handling Windows variants
-
-if not "%OS%" == "Windows_NT" goto win9xME_args
-
-:win9xME_args
-@rem Slurp the command line arguments.
-set CMD_LINE_ARGS=
-set _SKIP=2
-
-:win9xME_args_slurp
-if "x%~1" == "x" goto execute
-
-set CMD_LINE_ARGS=%*
-
 :execute
 @rem Setup the command line
 
 set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
 
+
 @rem Execute Gradle
-"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %CMD_LINE_ARGS%
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
 
 :end
 @rem End local scope for the variables with windows NT shell
diff --git a/settings.gradle b/settings.gradle
index 9d7221f..42d6695 100644
--- a/settings.gradle
+++ b/settings.gradle
@@ -1 +1,3 @@
 rootProject.name = "base91"
+
+enableFeaturePreview('ONE_LOCKFILE_PER_PROJECT')