Update Spring Framework to 6.0.20

Author: Corneil du Plessis

pom.xml

@@ -124,11 +124,11 @@
         <smack.version>4.3.5</smack.version>
 
         <!-- Spring Framework/Spring Security baseline -->
-        <spring.version>6.0.18</spring.version> <!-- TODO: Ensure smoke-tests matches, also check spring-next-gen -->
+        <spring.version>6.0.20</spring.version> <!-- TODO: Ensure smoke-tests matches, also check spring-next-gen -->
         <spring-security.version>6.1.9</spring-security.version>
 
         <!-- Spring Framework/Spring Security baseline-SNAPSHOT -->
-        <spring-snapshot.version>6.0.19-SNAPSHOT</spring-snapshot.version>
+        <spring-snapshot.version>6.0.21-SNAPSHOT</spring-snapshot.version>
         <spring-security-snapshot.version>6.1.10-SNAPSHOT</spring-security-snapshot.version>
 
         <!-- Spring Framework/Spring Security Next Gen -->
@@ -152,7 +152,7 @@
         <xmlunit.version>2.10.0</xmlunit.version>
         <xom.version>1.3.7</xom.version>
         <bouncycastle.version>1.77</bouncycastle.version>
-        <spring-asciidoctor-backends.version>0.0.3</spring-asciidoctor-backends.version>
+        <spring-asciidoctor-backends.version>0.0.5</spring-asciidoctor-backends.version>
     </properties>
 
     <dependencyManagement>
@@ -702,12 +702,12 @@
                     <plugin>
                         <groupId>org.asciidoctor</groupId>
                         <artifactId>asciidoctor-maven-plugin</artifactId>
-                        <version>2.2.2</version>
+                        <version>2.2.6</version>
                         <dependencies>
                             <dependency>
                                 <groupId>org.asciidoctor</groupId>
                                 <artifactId>asciidoctorj-pdf</artifactId>
-                                <version>2.3.0</version>
+                                <version>2.3.15</version>
                             </dependency>
                             <dependency>
                                 <groupId>io.spring.asciidoctor.backends</groupId>
@@ -726,8 +726,8 @@
                                 <configuration>
                                     <backend>spring-html</backend>
                                     <outputDirectory>${project.build.directory}/site/reference/html</outputDirectory>
-                                    <sourceHighlighter>highlight.js</sourceHighlighter>
                                     <attributes>
+                                        <sourceHighlighter>highlight.js</sourceHighlighter>
                                         // these attributes are required to use the doc resources
                                         <docinfo>shared</docinfo>
                                         <stylesdir>css/</stylesdir>
@@ -751,7 +751,9 @@
                                 <configuration>
                                     <outputDirectory>${project.build.directory}/site/reference/pdf</outputDirectory>
                                     <backend>pdf</backend>
-                                    <sourceHighlighter>coderay</sourceHighlighter>
+                                    <attributes>
+                                        <sourceHighlighter>coderay</sourceHighlighter>
+                                    </attributes>
                                 </configuration>
                             </execution>