forUseAtConfigurationTime compatibility

src/main/kotlin/io/github/gradlenexus/publishplugin/NexusPublishPlugin.kt

@@ -102,8 +102,8 @@ class NexusPublishPlugin : Plugin<Project> {
             stagingRepositoryId.convention(registryService.map { it.registry[repository.get().name].stagingRepositoryId })
         }
         extension.repositories.all {
-            username.convention(rootProject.providers.gradleProperty("${name}Username"))
-            password.convention(rootProject.providers.gradleProperty("${name}Password"))
+            username.convention(rootProject.providers.gradleProperty("${name}Username").forUseAtConfigurationTimeCompat())
+            password.convention(rootProject.providers.gradleProperty("${name}Password").forUseAtConfigurationTimeCompat())
             publicationType.convention(PublicationType.MAVEN)
             configureRepositoryTasks(rootProject.tasks, extension, this, registryService)
         }
@@ -380,3 +380,17 @@ private inline fun <reified T : Any> Project.theExtension(): T =
         this.extensions.findByType(it)
             ?: error("The plugin cannot be applied without the publishing plugin")
     }
+
+private fun <T> Provider<T>.forUseAtConfigurationTimeCompat(): Provider<T> =
+    if (GradleVersion.current() < GradleVersion.version("6.5")) {
+        // Gradle < 6.5 doesn't have this function.
+        this
+    } else if (GradleVersion.current() < GradleVersion.version("7.4")) {
+        // Gradle 6.5 - 7.3 requires this function to be called.
+        @Suppress("DEPRECATION")
+        this.forUseAtConfigurationTime()
+    } else {
+        // Gradle >= 7.4 deprecated this function in favor of not calling it (became no-op, and will eventually nag).
+        // https://docs.gradle.org/current/userguide/upgrading_version_7.html#for_use_at_configuration_time_deprecation
+        this
+    }