Or, you know, KISS and just get rid of the inheritance...

Revert the whole bytecode approach, just remove the tight coupling
introduced by the inheritance and it's compatible with all Lucene
versions without nasty hacks.

pom.xml

@@ -223,6 +223,23 @@
           </execution>
         </executions>
       </plugin>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-javadoc-plugin</artifactId>
+        <version>${version.maven-javadoc-plugin}</version>
+        <configuration>
+          <additionalOptions>-Xdoclint:none</additionalOptions>
+          <additionalJOption>-Xdoclint:none</additionalJOption>
+        </configuration>
+        <executions>
+          <execution>
+            <id>attach-javadocs</id>
+            <goals>
+              <goal>jar</goal>
+            </goals>
+          </execution>
+        </executions>
+      </plugin>
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-source-plugin</artifactId>

src/main/java/com/github/dbmdz/solrocr/lucene/OcrFieldHighlighter.java

@@ -38,21 +38,33 @@
 import org.apache.lucene.search.uhighlight.FieldOffsetStrategy;
 import org.apache.lucene.search.uhighlight.OffsetsEnum;
 import org.apache.lucene.search.uhighlight.Passage;
+import org.apache.lucene.search.uhighlight.PassageFormatter;
 import org.apache.lucene.search.uhighlight.PassageScorer;
+import org.apache.lucene.search.uhighlight.UnifiedHighlighter;
 import org.apache.lucene.util.BytesRef;
 
 /** A customization of {@link FieldHighlighter} to support OCR fields */
-public class OcrFieldHighlighter extends FieldHighlighterAdapter {
+public class OcrFieldHighlighter {
   private final ConcurrentHashMap<Integer, Integer> numMatches;
 
+  private final String field;
+  private final FieldOffsetStrategy fieldOffsetStrategy;
+  private final PassageScorer passageScorer;
+  private final int maxPassages;
+  private final int maxNoHighlightPassages;
+
   public OcrFieldHighlighter(
       String field,
       FieldOffsetStrategy fieldOffsetStrategy,
       PassageScorer passageScorer,
       int maxPassages,
       int maxNoHighlightPassages) {
-    super(field, fieldOffsetStrategy, passageScorer, maxPassages, maxNoHighlightPassages);
     this.numMatches = new ConcurrentHashMap<>();
+    this.field = field;
+    this.fieldOffsetStrategy = fieldOffsetStrategy;
+    this.passageScorer = passageScorer;
+    this.maxPassages = maxPassages;
+    this.maxNoHighlightPassages = maxNoHighlightPassages;
   }
 
   /**
@@ -111,7 +123,6 @@ public OcrSnippet[] highlightFieldForDoc(
     }
   }
 
-  @Override
   protected Passage[] highlightOffsetsEnums(OffsetsEnum off) {
     throw new UnsupportedOperationException();
   }
@@ -265,11 +276,14 @@ private Passage maybeAddPassage(
   }
 
   /** We don't provide summaries if there is no highlighting, i.e. no matches in the OCR text */
-  @Override
   protected Passage[] getSummaryPassagesNoHighlight(int maxPassages) {
     return new Passage[] {};
   }
 
+  public UnifiedHighlighter.OffsetSource getOffsetSource() {
+    return this.fieldOffsetStrategy.getOffsetSource();
+  }
+
   public int getNumMatches(int docId) {
     return numMatches.getOrDefault(docId, -1);
   }