Minor access modifier adjustment to a couple of lucene90 backward compat types (#14695)

This commit makes a minor adjustment to a couple of lucene90 backward compat types to avoid duplicating them for older code.

Author: ChrisHegarty

lucene/backward-codecs/src/java/org/apache/lucene/backward_codecs/lucene90/blocktree/CompressionAlgorithm.java

@@ -21,23 +21,24 @@
 import org.apache.lucene.util.compress.LowercaseAsciiCompression;
 
 /** Compression algorithm used for suffixes of a block of terms. */
-enum CompressionAlgorithm {
+public enum CompressionAlgorithm {
+  /** No compression. */
   NO_COMPRESSION(0x00) {
 
     @Override
     void read(DataInput in, byte[] out, int len) throws IOException {
       in.readBytes(out, 0, len);
     }
   },
-
+  /** Lowercase Ascii compression. */
   LOWERCASE_ASCII(0x01) {
 
     @Override
     void read(DataInput in, byte[] out, int len) throws IOException {
       LowercaseAsciiCompression.decompress(in, out, len);
     }
   },
-
+  /** LZ4 compression. */
   LZ4(0x02) {
 
     @Override
@@ -62,6 +63,7 @@ static final CompressionAlgorithm byCode(int code) {
     return BY_CODE[code];
   }
 
+  /** Compression code. */
   public final int code;
 
   private CompressionAlgorithm(int code) {

lucene/backward-codecs/src/java/org/apache/lucene/backward_codecs/lucene90/blocktree/Lucene90BlockTreeTermsReader.java

@@ -75,9 +75,10 @@ public final class Lucene90BlockTreeTermsReader extends FieldsProducer {
   static final int OUTPUT_FLAG_HAS_TERMS = 0x2;
 
   /** Extension of terms file */
-  static final String TERMS_EXTENSION = "tim";
+  public static final String TERMS_EXTENSION = "tim";
 
-  static final String TERMS_CODEC_NAME = "BlockTreeTermsDict";
+  /** Extension of terms codec name */
+  public static final String TERMS_CODEC_NAME = "BlockTreeTermsDict";
 
   /** Initial terms format. */
   public static final int VERSION_START = 0;
@@ -94,14 +95,16 @@ public final class Lucene90BlockTreeTermsReader extends FieldsProducer {
   public static final int VERSION_CURRENT = VERSION_FST_CONTINUOUS_ARCS;
 
   /** Extension of terms index file */
-  static final String TERMS_INDEX_EXTENSION = "tip";
+  public static final String TERMS_INDEX_EXTENSION = "tip";
 
-  static final String TERMS_INDEX_CODEC_NAME = "BlockTreeTermsIndex";
+  /** Extension of terms index codec name */
+  public static final String TERMS_INDEX_CODEC_NAME = "BlockTreeTermsIndex";
 
   /** Extension of terms meta file */
-  static final String TERMS_META_EXTENSION = "tmd";
+  public static final String TERMS_META_EXTENSION = "tmd";
 
-  static final String TERMS_META_CODEC_NAME = "BlockTreeTermsMeta";
+  /** Extension of terms meta codec name */
+  public static final String TERMS_META_CODEC_NAME = "BlockTreeTermsMeta";
 
   // Open input to the main terms dict file (_X.tib)
   final IndexInput termsIn;