Support markdown javadoc

[manger]

Java 23+ supports markdown for javadoc, as per JEP 467: Markdown Documentation Comments. Spotless breaks the markdown javadoc when it tries to reformat it.

Consider a class with javadoc that has a long hyperlink. Spotless wants to move the link to a new line to
limit the line length, but fails to keep the /// prefix needed for markdown javadoc.

/// Hello, World!
///
/// See [JEP_467:_Markdown_Documentation_Comments](https://openjdk.org/jeps/467#abcdefghijklmnopqrstuvwxyz)
public class Hello {}

After applying Spotless:

/// Hello, World!
///
/// See
// [JEP_467:_Markdown_Documentation_Comments](https://openjdk.org/jeps/467#abcdefghijklmnopqrstuvwxyz)
public class Hello {}

The link no longer appears in the javadoc.

[jbduncan]

@manger Welcome!

The choice of formatters will most likely have an impact on where the cause of this issue lies. Can you share an minimal, reproducible example with us?

[manger]

Minimal reproducible example:

Java code is as in the issue: src/main/java/Hello.java

/// Hello, World!
///
/// See [JEP_467:_Markdown_Documentation_Comments](https://openjdk.org/jeps/467#abcdefghijklmnopqrstuvwxyz)
public class Hello {}

Gradle Kotlin build file: build.gradle.kts

plugins {
  java
  id("com.diffplug.spotless") version "7.0.3"
}

repositories {
  mavenCentral()
}

java {
  toolchain {
    languageVersion = JavaLanguageVersion.of(23)
  }
}

spotless {
  java {
    googleJavaFormat()
  }
}

Tools:

• Java: openjdk version "23.0.1" 2024-10-15
• Gradle: Gradle 8.13 (Kotlin: 2.0.21, Groovy: 3.0.22, OS: Mac OS X 15.4 aarch64)

Javadoc (gradle javadoc) correctly includes the link iff Spotless has not been applied: build/docs/javadoc/Hello.html

<p>Hello, World!</p>
<p>See <a href="https://openjdk.org/jeps/467#abcdefghijklmnopqrstuvwxyz">JEP_467:_Markdown_Documentation_Comments</a></p>

After applying Spotless (gradle spotlessApply) the link is wrapped onto a new line without keeping the /// prefix required for markdown: src/main/java/Hello.java

/// Hello, World!
///
/// See
// [JEP_467:_Markdown_Documentation_Comments](https://openjdk.org/jeps/467#abcdefghijklmnopqrstuvwxyz)
public class Hello {}

Javadoc (gradle javadoc) is now missing the link: build/docs/javadoc/Hello.html

<p>Hello, World!</p>
<p>See</p>

Presumably googleJavaFormat needs to keep the /// prefix when wrapping long comments.