Add some documentation

benchmarks/workload-generator-commons/src/main/java/theodolite/commons/workloadgeneration/functions/MessageGenerator.java

 package theodolite.commons.workloadgeneration.functions;
 
+/**
+ * Interface representing a message generator, which sends messages for given keys to some
+ * destination.
+ */
 @FunctionalInterface
 public interface MessageGenerator {
 

benchmarks/workload-generator-commons/src/main/java/theodolite/commons/workloadgeneration/functions/RecordGenerator.java

 package theodolite.commons.workloadgeneration.functions;
 
 /**
- * This interface describes a function that takes meta information from a string (e.g. an ID) and
- * produces an object of type T.
+ * This interface describes a function that takes meta information from a string key and produces an
+ * object of type T.
  *
  * @param <T> the type of the objects that will be generated by the function.
  */

benchmarks/workload-generator-commons/src/main/java/theodolite/commons/workloadgeneration/functions/TitanMessageGeneratorFactory.java

@@ -4,6 +4,10 @@ import java.util.Properties;
 import theodolite.commons.workloadgeneration.communication.kafka.KafkaRecordSender;
 import titan.ccp.model.records.ActivePowerRecord;
 
+/**
+ * A factory for creating {@link MessageGenerator}s that creates Titan {@link ActivePowerRecord}s
+ * and sends them via Kafka.
+ */
 public final class TitanMessageGeneratorFactory {
 
   private final RecordSender<ActivePowerRecord> recordSender;
@@ -12,12 +16,19 @@ public final class TitanMessageGeneratorFactory {
     this.recordSender = recordSender;
   }
 
+  /**
+   * Create a {@link MessageGenerator} that generates Titan {@link ActivePowerRecord}s with a
+   * constant value.
+   */
   public MessageGenerator forConstantValue(final double value) {
     return MessageGenerator.from(
         sensor -> new ActivePowerRecord(sensor, System.currentTimeMillis(), value),
         this.recordSender);
   }
 
+  /**
+   * Create a new TitanMessageGeneratorFactory for the given Kafka configuration.
+   */
   public static TitanMessageGeneratorFactory withKafkaConfig(
       final String bootstrapServers,
       final String topic,
@@ -25,6 +36,9 @@ public final class TitanMessageGeneratorFactory {
     return withKafkaConfig(bootstrapServers, topic, schemaRegistryUrl, new Properties());
   }
 
+  /**
+   * Create a new TitanMessageGeneratorFactory for the given Kafka configuration.
+   */
   public static TitanMessageGeneratorFactory withKafkaConfig(
       final String bootstrapServers,
       final String topic,