Collecting data with streams - Java 8 in Action: Lambdas, Streams, and Functional-Style Programming - page 168

Figure 6.6. Combining the effect of multiple collectors by nesting one
inside the other
 The collectors are represented by the dashed lines, so groupingBy is the outermost one and groups
the menu stream into three substreams according to the different dishes' types.
 The groupingBy collector wraps the collectingAndThen collector, so each substream resulting
from the grouping operation is further reduced by this second collector.
 The collectingAndThen collector wraps in turn a third collector, the maxBy one.