Do not build Javadocs with JDK < 18

documentation/documentation.gradle

@@ -218,8 +218,8 @@ def aggregateJavadocsTask = tasks.register( "javadoc", Javadoc ) {
 				? javadocTool.get().metadata.languageVersion
 				: JavaLanguageVersion.of( JavaVersion.current().name )
 
-		if ( javaLanguageVersion.asInt() != 21 ) {
-			println "Aggregated Javadocs are bing built` using a JDK different than version 21: \n" +
+		if ( javaLanguageVersion.asInt() != 25 ) {
+			println "Aggregated Javadocs are bing built` using a JDK different than version 25: \n" +
 					"\t* `stylesheet.css` might not be compatible\n" +
 					"\t* generating the User Guide settings fragment might not succeed"
 		}
@@ -714,23 +714,38 @@ settingsDocumentation {
 def generateSettingsDocTask = tasks.named( "generateSettingsDoc" ) {
 	dependsOn aggregateJavadocsTask
 
-	doFirst {
-		def javadoc = aggregateJavadocsTask.get()
-		def javaLanguageVersion = javadoc.javadocTool.present
-				? javadoc.javadocTool.get().metadata.languageVersion
-				: JavaLanguageVersion.of( JavaVersion.current().name )
+    def javadoc = aggregateJavadocsTask.get()
+    def javaLanguageVersion = javadoc.javadocTool.present
+            ? javadoc.javadocTool.get().metadata.languageVersion
+            : JavaLanguageVersion.of( JavaVersion.current().name )
 
-		if ( javaLanguageVersion.asInt() > 11 ) {
-			println "Aggregated Javadocs was built using a JDK newer than version 11; generating the settings User Guide fragment will not succeed"
+	doFirst {
+		if ( javaLanguageVersion.asInt() != 25 ) {
+			println "Aggregated Javadocs were built using a JDK other than version 25; generating the settings User Guide fragment might not succeed"
 		}
 	}
+    onlyIf {
+        if (javaLanguageVersion.asInt() < 18) {
+            println "Javadocs require at least JDK 18 to be able to use some of the config options we rely on (e.g. --add-scripts). " +
+                    "Ignoring Javadoc rendering for this builds!"
+            return false
+        } else {
+            return true
+        }
+    }
 }
 
 def renderUserGuideHtmlTask = tasks.register( 'renderUserGuideHtml', AsciidoctorTask ) { task ->
 	group = "Documentation"
 	description = 'Renders the User Guides in HTML format using Asciidoctor.'
 	inputs.property "hibernate-version", hibernateVersion
-	inputs.file( generateSettingsDocTask.get().outputFile )
+    def javadoc = aggregateJavadocsTask.get()
+    def javaLanguageVersion = javadoc.javadocTool.present
+            ? javadoc.javadocTool.get().metadata.languageVersion
+            : JavaLanguageVersion.of( JavaVersion.current().name )
+    if (javaLanguageVersion.asInt() > 17) {
+        inputs.file( generateSettingsDocTask.get().outputFile )
+    }
 
 	dependsOn generateSettingsDocTask
 

documentation/src/main/asciidoc/userguide/appendices/SettingsReference.adoc

@@ -24,4 +24,4 @@ For (legacy) Hibernate settings which have a direct Jakarta Persistence corollar
 form should be preferred - e.g. `hibernate.connection.driver_class` -> `jakarta.persistence.jdbc.driver`.
 ====
 
-include::{doc-generated-content-dir}/config-settings.adoc[]
+include::{doc-generated-content-dir}/config-settings.adoc[opts=optional]

local-build-plugins/src/main/groovy/local.javadoc.gradle

@@ -77,4 +77,17 @@ tasks.withType(Javadoc).configureEach {
         docFilesSubDirs = true
     }
     dependsOn tasks.unpackTheme
+    onlyIf {
+        def javaLanguageVersion = javadocTool.present
+                ? javadocTool.get().metadata.languageVersion
+                : JavaLanguageVersion.of(JavaVersion.current().name)
+
+        if (javaLanguageVersion.asInt() < 18) {
+            println "Javadocs require at least JDK 18 to be able to use some of the config options we rely on (e.g. --add-scripts). " +
+                    "Ignoring Javadoc rendering for this builds!"
+            return false
+        } else {
+            return true
+        }
+    }
 }