Use a record to hold the compound symbol pair

Records have optimization characteristics that may be helpful
here.

core/src/main/java/org/jruby/RubySymbol.java

@@ -350,11 +350,11 @@ public static RubySymbol newHardSymbol(Ruby runtime, String name) {
     }
 
     public static RubySymbol newMethodSymbolFromCompound(Ruby runtime, String compoundName) {
-        return runtime.getSymbolTable().getCompoundSymbol(compoundName).getKey();
+        return runtime.getSymbolTable().getMethodSymbolFromCompound(compoundName);
     }
 
     public static RubySymbol newCalleeSymbolFromCompound(Ruby runtime, String compoundName) {
-        return runtime.getSymbolTable().getCompoundSymbol(compoundName).getValue();
+        return runtime.getSymbolTable().getCalleeSymbolFromCompound(compoundName);
     }
 
     /**
@@ -990,7 +990,7 @@ public static final class SymbolTable {
 
         private final ReentrantLock tableLock = new ReentrantLock();
         private volatile SymbolEntry[] symbolTable;
-        private Map<String, AbstractMap.SimpleImmutableEntry<RubySymbol, RubySymbol>> compoundSymbolTable = new ConcurrentHashMap<>();
+        private Map<String, CompoundSymbol> compoundSymbolTable = new ConcurrentHashMap<>();
         private int size;
         private int threshold;
         private final float loadFactor;
@@ -1105,6 +1105,29 @@ public RubySymbol getSymbol(ByteList bytes, ObjBooleanConsumer<RubySymbol> handl
             return symbol;
         }
 
+        /**
+         * Get the method name symbol from a compound name.
+         *
+         * @see #getCompoundSymbol(String)
+         * @param compoundName the compound name
+         * @return the method component of the compound name, as a symbol
+         */
+        public RubySymbol getMethodSymbolFromCompound(String compoundName) {
+            return getCompoundSymbol(compoundName).method;
+        }
+
+
+        /**
+         * Get the callee name symbol from a compound name.
+         *
+         * @see #getCompoundSymbol(String)
+         * @param compoundName the compound name
+         * @return the callee component of the compound name, as a symbol
+         */
+        public RubySymbol getCalleeSymbolFromCompound(String compoundName) {
+            return getCompoundSymbol(compoundName).callee;
+        }
+
         /**
          * Get a pair of symbols associated with the given compound method name, used by aliases to pass both the callee
          * name and the original method name on the stack. This avoids re-parsing the compoundName and constructing new
@@ -1113,13 +1136,15 @@ public RubySymbol getSymbol(ByteList bytes, ObjBooleanConsumer<RubySymbol> handl
          * @param compoundName the compound name used for a combination of alias and method
          * @return a Map.Entry representing the __method__ and __callee__ symbols for that compound name as key and value
          */
-        public Map.Entry<RubySymbol, RubySymbol> getCompoundSymbol(String compoundName) {
+        private CompoundSymbol getCompoundSymbol(String compoundName) {
             return compoundSymbolTable.computeIfAbsent(compoundName, (cname) ->
-                    new AbstractMap.SimpleImmutableEntry(
+                    new CompoundSymbol(
                             getSymbol(Helpers.getSuperNameFromCompositeName(cname), true),
                             getSymbol(Helpers.getCalleeNameFromCompositeName(cname), true)));
         }
 
+        private record CompoundSymbol(RubySymbol method, RubySymbol callee){}
+
         private RubySymbol findSymbol(ByteList bytes, int hash, boolean hard) {
             RubySymbol symbol = null;