Add key1()/key2() accessors to Hashtable.D2.Entry

internal-api/src/main/java/datadog/trace/util/Hashtable.java

@@ -265,6 +265,16 @@ protected Entry(K1 key1, K2 key2) {
         this.key2 = key2;
       }
 
+      /** The first key part this entry was created with. */
+      public K1 key1() {
+        return this.key1;
+      }
+
+      /** The second key part this entry was created with. */
+      public K2 key2() {
+        return this.key2;
+      }
+
       public boolean matches(K1 key1, K2 key2) {
         return Objects.equals(this.key1, key1) && Objects.equals(this.key2, key2);
       }

internal-api/src/test/java/datadog/trace/util/HashtableD2Test.java

@@ -137,6 +137,13 @@ void entryMatchesFalseWhenKey2Differs() {
     assertFalse(entry.matches("a", 2));
   }
 
+  @Test
+  void keyAccessorsExposeConstructionKeys() {
+    PairEntry entry = new PairEntry("a", 1, 100);
+    assertEquals("a", entry.key1());
+    assertEquals(1, entry.key2());
+  }
+
   @Test
   void entryHashIsConsistentForSameKeys() {
     long h1 = Hashtable.D2.Entry.hash("x", 42);