This PR introduces an optional version in RateLimitConfiguration,

which allows client code to replace the configuration on the fly.
Bucket4j checks the version against the persisted version, and replace
the configuration dynamically if version > persisted version.
[doc](https://bucket4j.com/8.8.0/toc.html#configuration-replacement)

GitOrigin-RevId: 8662847831bdaba6771062b0ab49699f04bd3bb0

samples/exemplar/src/main/kotlin/com/squareup/exemplar/actions/RateLimitedAction.kt

@@ -41,4 +41,5 @@ object ExampleRateLimitConfiguration : RateLimitConfiguration {
   override val name = "ExpensiveRateLimitedAction"
   override val refillAmount = 10L
   override val refillPeriod: Duration = Duration.ofMinutes(1L)
+  override val version = 0L // increment the version when updating the configuration
 }

wisp/wisp-rate-limiting/api/wisp-rate-limiting.api

@@ -3,6 +3,11 @@ public abstract interface class wisp/ratelimiting/RateLimitConfiguration {
 	public abstract fun getName ()Ljava/lang/String;
 	public abstract fun getRefillAmount ()J
 	public abstract fun getRefillPeriod ()Ljava/time/Duration;
+	public abstract fun getVersion ()Ljava/lang/Long;
+}
+
+public final class wisp/ratelimiting/RateLimitConfiguration$DefaultImpls {
+	public static fun getVersion (Lwisp/ratelimiting/RateLimitConfiguration;)Ljava/lang/Long;
 }
 
 public abstract interface class wisp/ratelimiting/RateLimitPruner {
@@ -119,5 +124,6 @@ public final class wisp/ratelimiting/testing/TestRateLimitConfig : wisp/ratelimi
 	public fun getName ()Ljava/lang/String;
 	public fun getRefillAmount ()J
 	public fun getRefillPeriod ()Ljava/time/Duration;
+	public fun getVersion ()Ljava/lang/Long;
 }
 

wisp/wisp-rate-limiting/bucket4j/src/main/kotlin/wisp/ratelimiting/bucket4j/Bucket4jRateLimiter.kt

@@ -4,6 +4,7 @@ import io.github.bucket4j.Bandwidth
 import io.github.bucket4j.BucketConfiguration
 import io.github.bucket4j.ConsumptionProbe
 import io.github.bucket4j.EstimationProbe
+import io.github.bucket4j.TokensInheritanceStrategy
 import io.github.bucket4j.distributed.BucketProxy
 import io.github.bucket4j.distributed.proxy.ProxyManager
 import io.micrometer.core.instrument.MeterRegistry
@@ -106,7 +107,11 @@ class Bucket4jRateLimiter @JvmOverloads constructor(
       .addLimit(configuration.toBandwidth())
       .build()
 
-    return bucketProxy.builder().build(key, bucketConfig)
+    return bucketProxy.builder().apply {
+      configuration.version?.let {
+        this.withImplicitConfigurationReplacement(it, TokensInheritanceStrategy.PROPORTIONALLY)
+      }
+    }.build(key, bucketConfig)
   }
 
   private fun RateLimitConfiguration.toBandwidth(): Bandwidth {

wisp/wisp-rate-limiting/src/main/kotlin/wisp/ratelimiting/RateLimitConfiguration.kt

@@ -26,4 +26,12 @@ interface RateLimitConfiguration {
    * The period of time over which [refillAmount] tokens are added back to the bucket
    */
   val refillPeriod: Duration
+
+  /**
+   * The version of the configuration. This allows implicit configuration replacement.
+   * Make sure to increase the version when changing the configuration.
+   * Desired version should start from 1
+   */
+  val version: Long?
+    get() = null // returns null to be backward compatible
 }