public class GroupByMany : ContainerModule, IModule, IModuleList, IList<IModule>

This module forms groups from the output documents of the specified modules. If the function or metadata key returns or contains an enumerable, each item in the enumerable will become one of the grouping keys. If a document contains multiple group keys, it will be included in multiple groups. A good example is a tag engine where each document can contain any number of tags and you want to make groups for each tag including all the documents with that tag. Each input document is cloned for each group and metadata related to the groups, including the sequence of documents for each group, is added to each clone. For example, if you have 2 input documents and the result of grouping is 3 groups, this module will output 6 documents.