This applies to all examples, but I first found the problem in Example 2.5 Using @AnalyzerDef and the Solr Framework to Define and Use an Analyzer


Describe the issue:
The example domain objects should never have any of these annotations:
- @Entity
- @GeneratedValue
- @DocumentId
- @Id
- @ManyToMany
- @ManyToOne
- @OneToMany

Also:
= the attributes usually annotated via @Id or @DocumentId need to be completely removed (not just the annotation).
= all example domain objects must implement Serializable

Suggestions for improvement:
For example the code for example 2.5 should be:

@Indexed
@AnalyzerDef(
   name = "customanalyzer",
   tokenizer = @TokenizerDef(factory = StandardTokenizerFactory.class),
   filters = {
      @TokenFilterDef(factory = LowerCaseFilterFactory.class), 
      @TokenFilterDef(factory = SnowballPorterFilterFactory.class,
         params = { @Parameter(name = "language", value = "English") })
 })
public class Book implements Serializable {

  @Field
  @Analyzer(definition = "customanalyzer")
  private String title;
  
  @Field
  @Analyzer(definition = "customanalyzer")
  private String subtitle; 

  @IndexedEmbedded
  private Set authors = new HashSet();

  @Field(index = Index.YES, analyze = Analyze.NO, store = Store.YES)
  @DateBridge(resolution = Resolution.DAY)
  private Date publicationDate;
  
  public Book() {
  } 
  
  // standard getters/setters follow here
  ... 
}

Finally, please take particular care with necessary vertical alignment in code. I realize it's not usually fundamental in text, but developers are particularly sensitive to finding it very disturbing.