Add a getImplementationName method to VectorizationProvider that returns the name of the selected implementation

Author: tflobbe

lucene/core/src/java/org/apache/lucene/internal/vectorization/VectorizationProvider.java

@@ -96,6 +96,11 @@ public static VectorizationProvider getInstance() {
         Holder.INSTANCE, "call to getInstance() from subclass of VectorizationProvider");
   }
 
+  /** Returns the name of the {@code VectorizationProvider}'s implementation that's being used. */
+  public static String getImplementationName() {
+    return Objects.requireNonNull(Holder.INSTANCE).getName();
+  }
+
   VectorizationProvider() {
     // no instance/subclass except from this package
   }
@@ -224,6 +229,10 @@ private static void ensureCaller() {
     }
   }
 
+  public String getName() {
+    return this.getClass().getSimpleName();
+  }
+
   /** This static holder class prevents classloading deadlock. */
   private static final class Holder {
     private Holder() {}

lucene/core/src/test/org/apache/lucene/internal/vectorization/TestVectorizationProvider.java

@@ -24,6 +24,10 @@ public void testCallerOfGetter() {
     expectThrows(UnsupportedOperationException.class, TestVectorizationProvider::illegalCaller);
   }
 
+  public void testGetProviderName() {
+    assertEquals("DefaultVectorizationProvider", VectorizationProvider.getImplementationName());
+  }
+
   private static void illegalCaller() {
     VectorizationProvider.getInstance();
   }