GH-403: Fix NPE in the CitcuitBreakerRetryPolicy

Fixes #403

The `openTimeout` resolution logic uses `this.resetTimeoutSupplier` by mistake

src/main/java/org/springframework/retry/policy/CircuitBreakerRetryPolicy.java

@@ -118,7 +118,7 @@ public RetryContext open(RetryContext parent) {
 			resetTimeout = this.resetTimeoutSupplier.get();
 		}
 		long openTimeout = this.openTimeout;
-		if (this.resetTimeoutSupplier != null) {
+		if (this.openTimeoutSupplier != null) {
 			openTimeout = this.openTimeoutSupplier.get();
 		}
 		return new CircuitBreakerRetryContext(parent, this.delegate, resetTimeout, openTimeout);