Allow FixedBackOff to be constructed with only a custom interval

This commit introduces two new constructors:

- FixedBackOff(long)

- FixedBackOff(Duration)

Closes gh-35028

spring-core/src/main/java/org/springframework/core/retry/RetryTemplate.java

@@ -16,6 +16,7 @@
 
 package org.springframework.core.retry;
 
+import java.time.Duration;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -60,7 +61,7 @@ public class RetryTemplate implements RetryOperations {
 
 	protected RetryPolicy retryPolicy = new MaxRetryAttemptsPolicy();
 
-	protected BackOff backOffPolicy = new FixedBackOff(1000, Long.MAX_VALUE);
+	protected BackOff backOffPolicy = new FixedBackOff(Duration.ofSeconds(1));
 
 	protected RetryListener retryListener = new RetryListener() {
 	};

spring-core/src/main/java/org/springframework/util/backoff/FixedBackOff.java

@@ -16,6 +16,8 @@
 
 package org.springframework.util.backoff;
 
+import java.time.Duration;
+
 /**
  * A simple {@link BackOff} implementation that provides a fixed interval
  * between two attempts and a maximum number of retries.
@@ -50,6 +52,28 @@ public class FixedBackOff implements BackOff {
 	public FixedBackOff() {
 	}
 
+	/**
+	 * Create an instance with the supplied interval and an unlimited number of
+	 * attempts.
+	 * @param interval the interval between two attempts in milliseconds
+	 * @since 7.0
+	 * @see #setMaxAttempts(long)
+	 */
+	public FixedBackOff(long interval) {
+		this.interval = interval;
+	}
+
+	/**
+	 * Create an instance with the supplied interval and an unlimited number of
+	 * attempts.
+	 * @param interval the interval between two attempts
+	 * @since 7.0
+	 * @see #setMaxAttempts(long)
+	 */
+	public FixedBackOff(Duration interval) {
+		this.interval = interval.toMillis();
+	}
+
 	/**
 	 * Create an instance with the supplied interval and maximum number of attempts.
 	 * @param interval the interval between two attempts in milliseconds

spring-core/src/test/java/org/springframework/core/retry/RetryTemplateTests.java

@@ -16,6 +16,8 @@
 
 package org.springframework.core.retry;
 
+import java.time.Duration;
+
 import org.junit.jupiter.api.Test;
 
 import org.springframework.core.retry.support.MaxRetryAttemptsPolicy;
@@ -55,7 +57,7 @@ class RetryTemplateTests {
 			}
 		};
 
-		retryTemplate.setBackOffPolicy(new FixedBackOff(100, Long.MAX_VALUE));
+		retryTemplate.setBackOffPolicy(new FixedBackOff(Duration.ofMillis(10)));
 
 		assertThat(retryTemplate.execute(retryable)).isEqualTo("hello world");
 	}
@@ -76,7 +78,7 @@ class RetryTemplateTests {
 			}
 		};
 
-		retryTemplate.setBackOffPolicy(new FixedBackOff(100, Long.MAX_VALUE));
+		retryTemplate.setBackOffPolicy(new FixedBackOff(Duration.ofMillis(10)));
 
 		assertThatExceptionOfType(RetryException.class)
 				.isThrownBy(() -> retryTemplate.execute(retryable))
@@ -123,7 +125,7 @@ class RetryTemplateTests {
 			}
 		};
 		retryTemplate.setRetryPolicy(retryPolicy);
-		retryTemplate.setBackOffPolicy(new FixedBackOff(100, Long.MAX_VALUE));
+		retryTemplate.setBackOffPolicy(new FixedBackOff(Duration.ofMillis(10)));
 
 		assertThatExceptionOfType(RetryException.class)
 				.isThrownBy(() -> retryTemplate.execute(retryable))