Configurations: Minor cleanups

Author: rozza

src/main/java/com/mongodb/kafka/connect/sink/MongoSinkConfig.java

@@ -48,10 +48,11 @@
 
 public class MongoSinkConfig extends AbstractConfig {
 
+  private static final String EMPTY_STRING = "";
   public static final String TOPICS_CONFIG = MongoSinkConnector.TOPICS_CONFIG;
   private static final String TOPICS_DOC =
       "A list of kafka topics for the sink connector, separated by commas";
-  public static final String TOPICS_DEFAULT = "";
+  public static final String TOPICS_DEFAULT = EMPTY_STRING;
   private static final String TOPICS_DISPLAY = "The Kafka topics";
 
   public static final String TOPICS_REGEX_CONFIG = "topics.regex";
@@ -63,7 +64,7 @@ public class MongoSinkConfig extends AbstractConfig {
           + " or "
           + TOPICS_REGEX_CONFIG
           + " should be specified.";
-  public static final String TOPICS_REGEX_DEFAULT = "";
+  public static final String TOPICS_REGEX_DEFAULT = EMPTY_STRING;
   private static final String TOPICS_REGEX_DISPLAY = "Topics regex";
 
   public static final String CONNECTION_URI_CONFIG = "connection.uri";
@@ -74,7 +75,7 @@ public class MongoSinkConfig extends AbstractConfig {
           + "eg: ``mongodb://user@pass@locahost/``.";
 
   public static final String TOPIC_OVERRIDE_CONFIG = "topic.override.%s.%s";
-  private static final String TOPIC_OVERRIDE_DEFAULT = "";
+  private static final String TOPIC_OVERRIDE_DEFAULT = EMPTY_STRING;
   private static final String TOPIC_OVERRIDE_DISPLAY = "Per topic configuration overrides.";
   public static final String TOPIC_OVERRIDE_DOC =
       "The overrides configuration allows for per topic customization of configuration. "

src/main/java/com/mongodb/kafka/connect/source/MongoSourceConfig.java

@@ -59,6 +59,7 @@
 
 public class MongoSourceConfig extends AbstractConfig {
 
+  private static final String EMPTY_STRING = "";
   private static final Pattern CLASS_NAME =
       Pattern.compile("\\p{javaJavaIdentifierStart}\\p{javaJavaIdentifierPart}*");
   private static final Pattern FULLY_QUALIFIED_CLASS_NAME =
@@ -142,14 +143,14 @@ public class MongoSourceConfig extends AbstractConfig {
       "Prefix to prepend to database & collection names to generate the name of the Kafka "
           + "topic to publish data to. Used by the 'DefaultTopicMapper'.";
   private static final String TOPIC_PREFIX_DISPLAY = "Topic Prefix";
-  private static final String TOPIC_PREFIX_DEFAULT = "";
+  private static final String TOPIC_PREFIX_DEFAULT = EMPTY_STRING;
 
   public static final String TOPIC_SUFFIX_CONFIG = "topic.suffix";
   private static final String TOPIC_SUFFIX_DOC =
       "Suffix to append to database & collection names to generate the name of the Kafka "
           + "topic to publish data to. Used by the 'DefaultTopicMapper'.";
   private static final String TOPIC_SUFFIX_DISPLAY = "Topic Suffix";
-  private static final String TOPIC_SUFFIX_DEFAULT = "";
+  private static final String TOPIC_SUFFIX_DEFAULT = EMPTY_STRING;
 
   public static final String TOPIC_NAMESPACE_MAP_CONFIG = "topic.namespace.map";
   private static final String TOPIC_NAMESPACE_MAP_DISPLAY = "The namespace to topic map";
@@ -163,7 +164,7 @@ public class MongoSourceConfig extends AbstractConfig {
           + "will map all change stream documents to the `everyThingTopic` apart from the `db.coll` "
           + "messages."
           + "Note: Any prefix and suffix configuration will still apply.";
-  private static final String TOPIC_NAMESPACE_MAP_DEFAULT = "";
+  private static final String TOPIC_NAMESPACE_MAP_DEFAULT = EMPTY_STRING;
 
   public static final String PIPELINE_CONFIG = "pipeline";
   private static final String PIPELINE_DISPLAY = "The pipeline to apply to the change stream";
@@ -192,14 +193,14 @@ public class MongoSourceConfig extends AbstractConfig {
           + "When set to 'updateLookup', the change stream for partial updates will include both a delta "
           + "describing the changes to the document as well as a copy of the entire document that was changed from *some time* after "
           + "the change occurred.";
-  private static final String FULL_DOCUMENT_DEFAULT = "";
+  private static final String FULL_DOCUMENT_DEFAULT = EMPTY_STRING;
 
   public static final String COLLATION_CONFIG = "collation";
   private static final String COLLATION_DISPLAY = "The collation options";
   private static final String COLLATION_DOC =
       "The json representation of the Collation options to use for the change stream.\n"
           + "Use the `Collation.asDocument().toJson()` to create the specific json representation.";
-  private static final String COLLATION_DEFAULT = "";
+  private static final String COLLATION_DEFAULT = EMPTY_STRING;
 
   public static final String POLL_MAX_BATCH_SIZE_CONFIG = "poll.max.batch.size";
   private static final String POLL_MAX_BATCH_SIZE_DISPLAY = "The maximum batch size";
@@ -218,14 +219,14 @@ public class MongoSourceConfig extends AbstractConfig {
   private static final String DATABASE_DISPLAY = "The database to watch.";
   private static final String DATABASE_DOC =
       "The database to watch. If not set then all databases will be watched.";
-  private static final String DATABASE_DEFAULT = "";
+  private static final String DATABASE_DEFAULT = EMPTY_STRING;
 
   public static final String COLLECTION_CONFIG = "collection";
   private static final String COLLECTION_DISPLAY = "The collection to watch.";
   private static final String COLLECTION_DOC =
       "The collection in the database to watch. If not set then all collections will be "
           + "watched.";
-  private static final String COLLECTION_DEFAULT = "";
+  private static final String COLLECTION_DEFAULT = EMPTY_STRING;
 
   public static final String COPY_EXISTING_CONFIG = "copy.existing";
   private static final String COPY_EXISTING_DISPLAY = "Copy existing data";
@@ -260,7 +261,7 @@ public class MongoSourceConfig extends AbstractConfig {
           + "This can improve the use of indexes by the copying manager and make copying more efficient.\n"
           + "Use if there is any filtering of collection data in the `pipeline` configuration to speed up the copying process.\n"
           + "Example: `[{\"$match\": {\"closed\": \"false\"}}]`";
-  private static final String COPY_EXISTING_PIPELINE_DEFAULT = "";
+  private static final String COPY_EXISTING_PIPELINE_DEFAULT = EMPTY_STRING;
 
   public static final String COPY_EXISTING_NAMESPACE_REGEX_CONFIG = "copy.existing.namespace.regex";
   private static final String COPY_EXISTING_NAMESPACE_REGEX_DISPLAY =
@@ -270,7 +271,7 @@ public class MongoSourceConfig extends AbstractConfig {
           + " A namespace is the database name and collection separated by a period e.g. `database.collection`.\n"
           + " Example: The following regular expression will only include collections starting with `a` "
           + "in the `demo` database: `demo\\.a.*`";
-  private static final String COPY_EXISTING_NAMESPACE_REGEX_DEFAULT = "";
+  private static final String COPY_EXISTING_NAMESPACE_REGEX_DEFAULT = EMPTY_STRING;
 
   public static final String ERRORS_TOLERANCE_CONFIG = "errors.tolerance";
   public static final String ERRORS_TOLERANCE_DISPLAY = "Error Tolerance";
@@ -299,7 +300,7 @@ public class MongoSourceConfig extends AbstractConfig {
       "errors.deadletterqueue.topic.name";
   public static final String ERRORS_DEAD_LETTER_QUEUE_TOPIC_NAME_DISPLAY =
       "Output errors to the dead letter queue";
-  public static final String ERRORS_DEAD_LETTER_QUEUE_TOPIC_NAME_DEFAULT = "";
+  public static final String ERRORS_DEAD_LETTER_QUEUE_TOPIC_NAME_DEFAULT = EMPTY_STRING;
   public static final String ERRORS_DEAD_LETTER_QUEUE_TOPIC_NAME_DOC =
       "Whether to output conversion errors to the dead letter queue. "
           + "Stops poison messages when using schemas, any message will be outputted as extended json on the specified topic. "
@@ -330,7 +331,7 @@ public class MongoSourceConfig extends AbstractConfig {
 
   public static final String OFFSET_PARTITION_NAME_CONFIG = "offset.partition.name";
   public static final String OFFSET_PARTITION_NAME_DISPLAY = "Offset partition name";
-  public static final String OFFSET_PARTITION_NAME_DEFAULT = "";
+  public static final String OFFSET_PARTITION_NAME_DEFAULT = EMPTY_STRING;
   public static final String OFFSET_PARTITION_NAME_DOC =
       "Use a custom offset partition name. If blank the default partition name based on the "
           + "connection details will be used.";