Clarify commons-pool2 requirement for redis

`JedisConnectionFactory` needs `commons-pool2` for quite some time now
and our auto-configuration had a special case to handle redis if
`commons-pool2` isn't available.

This commit removes that code as using it would lead to a failure anyway.

Closes gh-5718

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/data/redis/RedisAutoConfiguration.java

@@ -24,11 +24,10 @@ import org.apache.commons.pool2.impl.GenericObjectPool;
 import redis.clients.jedis.Jedis;
 import redis.clients.jedis.JedisPoolConfig;
 
-import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
-import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingClass;
 import org.springframework.boot.autoconfigure.data.redis.RedisProperties.Cluster;
 import org.springframework.boot.autoconfigure.data.redis.RedisProperties.Sentinel;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
@@ -55,31 +54,40 @@ import org.springframework.util.StringUtils;
  * @author Christoph Strobl
  * @author Phillip Webb
  * @author Eddú Meléndez
+ * @author Stephane Nicoll
  */
 @Configuration
 @ConditionalOnClass({ JedisConnection.class, RedisOperations.class, Jedis.class })
-@EnableConfigurationProperties
+@EnableConfigurationProperties(RedisProperties.class)
 public class RedisAutoConfiguration {
 
-	@Bean(name = "org.springframework.autoconfigure.redis.RedisProperties")
-	@ConditionalOnMissingBean
-	public RedisProperties redisProperties() {
-		return new RedisProperties();
-	}
-
 	/**
-	 * Base class for Redis configurations.
+	 * Redis connection configuration.
 	 */
-	protected static abstract class AbstractRedisConfiguration {
+	@Configuration
+	@ConditionalOnClass(GenericObjectPool.class)
+	protected static class RedisConnectionConfiguration {
+
+		private final RedisProperties properties;
 
-		@Autowired
-		protected RedisProperties properties;
+		private final RedisSentinelConfiguration sentinelConfiguration;
 
-		@Autowired(required = false)
-		private RedisSentinelConfiguration sentinelConfiguration;
+		private final RedisClusterConfiguration clusterConfiguration;
 
-		@Autowired(required = false)
-		private RedisClusterConfiguration clusterConfiguration;
+		public RedisConnectionConfiguration(RedisProperties properties,
+				ObjectProvider<RedisSentinelConfiguration> sentinelConfigurationProvider,
+				ObjectProvider<RedisClusterConfiguration> clusterConfigurationProvider) {
+			this.properties = properties;
+			this.sentinelConfiguration = sentinelConfigurationProvider.getIfAvailable();
+			this.clusterConfiguration = clusterConfigurationProvider.getIfAvailable();
+		}
+
+		@Bean
+		@ConditionalOnMissingBean(RedisConnectionFactory.class)
+		public JedisConnectionFactory redisConnectionFactory()
+				throws UnknownHostException {
+			return applyProperties(createJedisConnectionFactory());
+		}
 
 		protected final JedisConnectionFactory applyProperties(
 				JedisConnectionFactory factory) {
@@ -147,49 +155,6 @@ public class RedisAutoConfiguration {
 			return nodes;
 		}
 
-	}
-
-	/**
-	 * Redis connection configuration.
-	 */
-	@Configuration
-	@ConditionalOnMissingClass("org.apache.commons.pool2.impl.GenericObjectPool")
-	protected static class RedisConnectionConfiguration
-			extends AbstractRedisConfiguration {
-
-		@Bean
-		@ConditionalOnMissingBean(RedisConnectionFactory.class)
-		public JedisConnectionFactory redisConnectionFactory()
-				throws UnknownHostException {
-			return applyProperties(createJedisConnectionFactory());
-		}
-
-		private JedisConnectionFactory createJedisConnectionFactory() {
-			if (getSentinelConfig() != null) {
-				return new JedisConnectionFactory(getSentinelConfig());
-			}
-			if (getClusterConfiguration() != null) {
-				return new JedisConnectionFactory(getClusterConfiguration());
-			}
-			return new JedisConnectionFactory();
-		}
-	}
-
-	/**
-	 * Redis pooled connection configuration.
-	 */
-	@Configuration
-	@ConditionalOnClass(GenericObjectPool.class)
-	protected static class RedisPooledConnectionConfiguration
-			extends AbstractRedisConfiguration {
-
-		@Bean
-		@ConditionalOnMissingBean(RedisConnectionFactory.class)
-		public JedisConnectionFactory redisConnectionFactory()
-				throws UnknownHostException {
-			return applyProperties(createJedisConnectionFactory());
-		}
-
 		private JedisConnectionFactory createJedisConnectionFactory() {
 			JedisPoolConfig poolConfig = this.properties.getPool() != null
 					? jedisPoolConfig() : new JedisPoolConfig();