Upgrade com.diffplug.spotless to 7.2.1 in Java build (#26051)

This PR upgrades the com.diffplug.spotless Gradle plugin to version
7.2.1 in the java/build.gradle file. This brings in the latest features
and bug fixes from the Spotless code formatter.

Author: snnn

java/build.gradle

@@ -3,7 +3,7 @@ plugins {
 	id 'maven-publish'
 	id 'signing'
 	id 'jacoco'
-	id "com.diffplug.spotless" version "6.25.0"
+	id "com.diffplug.spotless" version "7.2.1"
 }
 
 allprojects {