anchor.diff:      }
   ----
   
  -However, that scales poorly because it doesn't do an <<incrementalScoreCalculation,incremental calculation>>:
  -When the planning variable of a single `Talk` changes, to recalculate the score,
  -the normal Streams API has to execute the entire stream from scratch.
  -
  -On the other hand, the ConstraintStreams API uses <<incrementalScoreCalculation,deltas>>:
  +However, this approach scales poorly because it does not perform an <<incrementalScoreCalculation,incremental calculation>>.
  +In the previous example,when the planning variable of a single `Talk` intety changes, to recalculate the score the Java streams package must execute the entire stream from scratch.
  +
  +//COMMENT: Lukas I have made the Java streams API lowercase and not code - it looks like it's a general term that includes specific packages, for exmpl java.util.stream. Let me know if I'm mistaken. Also, if I'm using 'package' incorrectly.
  +
  +On the other hand, the `ConstraintStreams` API uses <<incrementalScoreCalculation,deltas>>:
   
   ////
   TODO Replace the previous sentence when PLANNER-1709 is fixed.
  
positive.code: [collectorsCountDistinct]
  ==== Collecting `countDistinct()`
  
  The `ConstraintCollectors.countDistinct(...)` counts any element in a group once, regardless of how many times it
  occurs. For example, the following use of the collector gives a number of talks in each unique room.
  
  [source,java,options="nowrap"]
  ----
  
negative.code: 
  There are several collectors available out of the box. You can also provide your own collectors by implementing the
  `org.optaplanner.core.api.score.stream.uni.UniConstraintCollector` interface, or its `Bi...`, `Tri...` counterparts.
  //COMMENT: Can we be more specific about Bi and Tri?
  
  [collectorsOutOfTheBox]
  === Out-of-the-box collectors
  
  The following section describes the collector implementations provided out of the box. This section only describes the
  `int`-based variants of the collectors in detail. Many of the collectors also provide variants for other applicable result data types, such as `long`, `BigDecimal` or `Duration`. You can see a complete list in the `org.optaplanner.core.api.score.stream.ConstraintCollectors` class.
  
  [collectorsCount]
  ==== Collecting `count()`
  
  The `ConstraintCollectors.count(...)` counts all elements in a group. For example, the following use of the collector gives a number of items for two separate groups: one where the talks have unavailable speakers, and one where they do not unavailable speakers.
  
  [source,java,options="nowrap"]
  ----
  