LUCENE-9392: make FacetsConfig.DELIM_CHAR public

lucene/CHANGES.txt

@@ -204,6 +204,8 @@ Improvements
 * LUCENE-9393: Make FunctionScoreQuery use ScoreMode.COMPLETE for creating the inner query weight when
   ScoreMode.TOP_DOCS is requested. (Tomás Fernández Löbbe)
 
+* LUCENE-9392: Make FacetsConfig.DELIM_CHAR publicly accessible (Ankur Goel))
+
 Optimizations
 ---------------------
 

lucene/facet/src/java/org/apache/lucene/facet/FacetsConfig.java

@@ -496,8 +496,15 @@ public class FacetsConfig {
     }
   }
 
-  // Joins the path components together:
-  private static final char DELIM_CHAR = '\u001F';
+  /**
+   * Character used to join the category path components together into a single
+   * drill down term for indexing.  Applications and unit-tests can reference this for
+   * creating their own drill-down terms, or use existing APIs (for example,
+   * {@link #pathToString}).
+   *
+   * @lucene.internal
+   */
+  public static final char DELIM_CHAR = '\u001F';
 
   // Escapes any occurrence of the path component inside the label:
   private static final char ESCAPE_CHAR = '\u001E';