minor build improvements for eclipse sync

gradle/plugins/src/main/kotlin/lifecycle/eclipse.caffeine.gradle.kts

@@ -5,16 +5,23 @@ plugins {
  eclipse
 }
 
+val eclipsePreferences by tasks.registering {
+ description = "Generates the Eclipse preferences files."
+ doFirst {
+ addPreferences("org.eclipse.core.resources.prefs", mapOf(
+ "encoding/<project>" to "UTF-8"))
+ addPreferences("org.eclipse.jdt.core.prefs", mapOf(
+ "org.eclipse.jdt.core.compiler.problem.unusedWarningToken" to "ignore"))
+ }
+}
+
 eclipse {
  classpath.file.whenMerged {
  if (this is Classpath) {
  excludeInfoFiles(this)
  }
  }
- addPreferences("org.eclipse.core.resources.prefs", mapOf(
- "encoding/<project>" to "UTF-8"))
- addPreferences("org.eclipse.jdt.core.prefs", mapOf(
- "org.eclipse.jdt.core.compiler.problem.unusedWarningToken" to "ignore"))
+ synchronizationTasks(eclipsePreferences)
 }
 
 /** Exclude module-info and package-info when compiling through Eclipse. */
@@ -34,11 +41,11 @@ fun addPreferences(path: String, preferences: Map<String, String>) {
  val settings = file(".settings/$path")
  if (!settings.exists()) {
  settings.parentFile.mkdirs()
- settings.writeText("eclipse.preferences.version=1\n")
  }
+ val updates = preferences + ("eclipse.preferences.version" to "1")
  val text = settings.readLines()
- .filter { line -> line.substringBefore('=') !in preferences }
- .plus(preferences.map { (key, value) -> "$key=$value" })
+ .filter { line -> line.substringBefore('=') !in updates }
+ .plus(updates.map { (key, value) -> "$key=$value" })
  .joinToString(separator = "\n", postfix = "\n")
  settings.writeText(text)
 }