Remove GradleCompat and always use project providers for querying properties

Author: inorichi

plugin-gradle/src/main/java/com/diffplug/gradle/spotless/FormatExtension.java

@@ -634,7 +634,8 @@ public LicenseHeaderConfig updateYearWithLatest(boolean updateYearWithLatest) {
 
 		FormatterStep createStep() {
 			return builder.withYearModeLazy(() -> {
-				if (Boolean.parseBoolean(GradleCompat.findOptionalProperty(spotless.project, LicenseHeaderStep.FLAG_SET_LICENSE_HEADER_YEARS_FROM_GIT_HISTORY()))) {
+				String yearProperty = spotless.project.getProviders().gradleProperty(LicenseHeaderStep.FLAG_SET_LICENSE_HEADER_YEARS_FROM_GIT_HISTORY()).getOrNull();
+				if (Boolean.parseBoolean(yearProperty)) {
 					return YearMode.SET_FROM_GIT;
 				} else {
 					boolean updateYear = updateYearWithLatest == null ? getRatchetFrom() != null : updateYearWithLatest;

plugin-gradle/src/main/java/com/diffplug/gradle/spotless/GradleCompat.java

@@ -39,10 +39,10 @@ static class State extends NoLambda.EqualityBasedOnSerialization {
 		final boolean useStdOut;
 
 		State(Project project) {
-			var pathsString = GradleCompat.findOptionalProperty(project, PROPERTY);
+			var pathsString = project.getProviders().gradleProperty(PROPERTY).getOrNull();
 			if (pathsString != null) {
-				useStdIn = GradleCompat.isPropertyPresent(project, USE_STD_IN);
-				useStdOut = GradleCompat.isPropertyPresent(project, USE_STD_OUT);
+				useStdIn = project.getProviders().gradleProperty(USE_STD_IN).isPresent();
+				useStdOut = project.getProviders().gradleProperty(USE_STD_OUT).isPresent();
 				paths = Arrays.stream(pathsString.split(","))
 						.map(String::trim)
 						.filter(s -> !s.isEmpty())

plugin-gradle/src/main/java/com/diffplug/gradle/spotless/IdeHook.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2025 DiffPlug
+ * Copyright 2016-2026 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -42,7 +42,7 @@ public void apply(Project project) {
 					+ "https://docs.gradle.org/current/userguide/building_java_projects.html#sec:java_cross_compilation");
 		}
 		// if -PspotlessModern=true, then use the modern stuff instead of the legacy stuff
-		if (GradleCompat.isPropertyPresent(project, SPOTLESS_MODERN)) {
+		if (project.getProviders().gradleProperty(SPOTLESS_MODERN).isPresent()) {
 			project.getLogger().warn("'spotlessModern' has no effect as of Spotless 5.0, recommend removing it.");
 		}
 		// make sure there's a `clean` and a `check`