diff --git a/build.gradle b/build.gradle
index 815fb660..b716af78 100644
--- a/build.gradle
+++ b/build.gradle
@@ -2,14 +2,13 @@ buildscript {
 	repositories {
 		maven { url "https://repo.spring.io/plugins-release" }
 	}
-	dependencies {
-		classpath("org.asciidoctor:asciidoctor-gradle-plugin:1.5.9.2")
-		classpath "org.asciidoctor:asciidoctorj-pdf:1.5.0-alpha.16"
-	}
 }
 
 plugins {
 	id 'io.spring.dependency-management' version '1.0.9.RELEASE' apply false
+	id 'org.asciidoctor.jvm.pdf' version '3.3.0'
+	id 'org.asciidoctor.jvm.gems' version '3.3.0'
+	id 'org.asciidoctor.jvm.convert' version '3.3.0'
 }
 
 ext {
@@ -166,7 +165,7 @@ configure(rootProject) {
 	}
 
 	ext {
-		docResourcesVersion = "0.2.1.RELEASE"
+		docResourcesVersion = "0.2.5"
 	}
 
 	dependencies {
@@ -185,54 +184,62 @@ configure(rootProject) {
 		into "$buildDir/asciidoc/build"
 	}
 
-	apply plugin: 'org.asciidoctor.convert'
-
-	task('makePDF', type: org.asciidoctor.gradle.AsciidoctorTask) {
+	asciidoctorPdf {
 		dependsOn prepareAsciidocBuild
-		onlyIf { !project.version.endsWith("SNAPSHOT") }
-		backends 'pdf'
-		sourceDir "$buildDir/asciidoc/build"
-		sources {
-			include 'index.adoc'
-		}
-		options doctype: 'book', eruby: 'erubis'
-		logDocuments = true
-		attributes 'icons': 'font',
+		baseDirFollowsSourceFile()
+
+		asciidoctorj {
+			sourceDir "$buildDir/asciidoc/build"
+			inputs.dir(sourceDir)
+			sources {
+				include 'index.adoc'
+			}
+			options doctype: 'book'
+			attributes 'icons': 'font',
 			'sectanchors': '',
+			'sectnums': '',
 			'toc': '',
 			'source-highlighter' : 'coderay',
-			revnumber: project.version
+			revnumber: project.version,
+			'project-version': project.version
+		}
 	}
 
 	asciidoctor {
-		dependsOn makePDF
-		// run asciidoctor from that directory
+		dependsOn asciidoctorPdf
+
+		baseDirFollowsSourceFile()
+
 		sourceDir "$buildDir/asciidoc/build"
-		sources {
-			include 'index.adoc'
-		}
+		inputs.dir(sourceDir)
 		resources {
 			from(sourceDir) {
 				include 'images/*', 'css/**', 'js/**'
 			}
 		}
-		logDocuments = true
-		backends = ["html5"]
-		options doctype: 'book', eruby: 'erubis'
-		attributes  'docinfo': 'shared',
-			// use provided stylesheet
-			stylesdir: "css/",
+		options doctype: 'book'
+
+		attributes 'docinfo': 'shared',
+			stylesdir: 'css/',
 			stylesheet: 'spring.css',
 			'linkcss': true,
 			'icons': 'font',
-			// use provided highlighter
-			'source-highlighter=highlight.js',
-			'highlightjsdir=js/highlight',
-			'highlightjs-theme=github',
-			revnumber: project.version
+			'sectanchors': '',
+			'source-highlighter': 'highlight.js',
+			'highlightjsdir': 'js/highlight',
+			'highlightjs-theme': 'github',
+			'idprefix': '',
+			'idseparator': '-',
+			'spring-version': project.version,
+			'allow-uri-read': '',
+			'toc': 'left',
+			'toclevels': '4',
+			revnumber: project.version,
+			'project-version': project.version
 	}
 
-	// don"t publish the default jar for the root project
+
+	// don't publish the default jar for the root project
 	configurations.archives.artifacts.clear()
 
 	artifacts {
@@ -275,7 +282,7 @@ configure(rootProject) {
 			into "reference"
 		}
 
-		from (makePDF) {
+		from (asciidoctorPdf) {
 			include "*.pdf"
 			into "reference"
 		}
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
index 5c2d1cf0..e708b1c0 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 5028f28f..12d38de6 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-5.6.4-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.6.1-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
diff --git a/gradlew b/gradlew
index 83f2acfd..4f906e0c 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
@@ -129,6 +130,7 @@ fi
 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 [ "$cygwin" = "true" -o "$msys" = "true" ] ; 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 24467a14..ac1b06f9 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