HADOOP-18371. S3A FS init to log at debug when fs.s3a.create.storage.class is unset (#4730)

Contributed By: Viraj Jasani

hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/S3AFileSystem.java

@@ -1005,13 +1005,17 @@ public class S3AFileSystem extends FileSystem implements StreamCapabilities,
     String storageClassConf = getConf()
         .getTrimmed(STORAGE_CLASS, "")
         .toUpperCase(Locale.US);
-    StorageClass storageClass;
-    try {
-      storageClass = StorageClass.fromValue(storageClassConf);
-    } catch (IllegalArgumentException e) {
-      LOG.warn("Unknown storage class property {}: {}; falling back to default storage class",
-          STORAGE_CLASS, storageClassConf);
-      storageClass = null;
+    StorageClass storageClass = null;
+    if (!storageClassConf.isEmpty()) {
+      try {
+        storageClass = StorageClass.fromValue(storageClassConf);
+      } catch (IllegalArgumentException e) {
+        LOG.warn("Unknown storage class property {}: {}; falling back to default storage class",
+            STORAGE_CLASS, storageClassConf);
+      }
+    } else {
+      LOG.debug("Unset storage class property {}; falling back to default storage class",
+          STORAGE_CLASS);
     }
 
     return RequestFactoryImpl.builder()