Polish "Clarify cache configuration"

Closes gh-335

src/main/java/org/springframework/samples/petclinic/system/CacheConfiguration.java

 package org.springframework.samples.petclinic.system;
 
-import javax.cache.configuration.MutableConfiguration;
-
 import org.springframework.boot.autoconfigure.cache.JCacheManagerCustomizer;
 import org.springframework.cache.annotation.EnableCaching;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 
+import javax.cache.configuration.MutableConfiguration;
+
 /**
- * Cache configuration intended for caches providing the JCache API. This configuration
- * creates the used cache for the application and enables statistics that
- * become accessible via JMX.
- *
- * <p>This is a minimal configuration that makes use of the JCache API to enable
- * caching with any JCache implementation out of the box. The utilized JCache implementation
- * is specified by the dependency in the {@code pom.xml}.
- *
- * <p>If the used cache implementation is configured via its specific and non standard mechanism,
- * this example configuration might be redundant and can be removed or replaced by
- * a programmatic configuration via the implementation specific methods.
- *
- * <p>In case no programmatic cache configuration is needed for the selected caching
- * implementation this configuration class can be removed and the {@link EnableCaching}
- * annotation can be put on the application class.
- *
- * @author Jens Wilke
+ * Cache configuration intended for caches providing the JCache API. This configuration creates the used cache for the
+ * application and enables statistics that become accessible via JMX.
  */
 @Configuration
 @EnableCaching
 class CacheConfiguration {
 
-    /**
-     * A customizer that creates the the cache used by the application.
-     * This implies that the cache is not existent before the application start and the
-     * cache must be created. This is the default behavior of a JCache implemenation, in case
-     * no additional configuration is present and typically will create a transient in memory cache.
-     * If a persistent cache implementation is used, creating the cache on startup
-     * may lead to a failure, when the cache was created before. If the cache life time
-     * is controlled separately, the call of {@code createCache} must be removed.
-     */
     @Bean
     public JCacheManagerCustomizer petclinicCacheConfigurationCustomizer() {
         return cm -> {
@@ -47,11 +23,11 @@ class CacheConfiguration {
     }
 
     /**
-     * Enable statistics via the JCache programmatic configuration API.
-     * Within the configuration object that is provided by the JCache API standard, there is only
-     * a very limited set of configuration options. The really relevant configuration options
-     * (like the size limit) must be set via a configuration mechanism that is provided by the
-     * selected JCache implementation.
+     * Create a simple configuration that enable statistics via the JCache programmatic configuration API.
+     * <p>
+     * Within the configuration object that is provided by the JCache API standard, there is only a very limited set of
+     * configuration options. The really relevant configuration options (like the size limit) must be set via a
+     * configuration mechanism that is provided by the selected JCache implementation.
      */
     private javax.cache.configuration.Configuration<Object, Object> cacheConfiguration() {
         return new MutableConfiguration<>().setStatisticsEnabled(true);