private static final Map<Character, Integer> TYPE_TO_RET =
                         new HashMap<Character, Integer>();

static {
    TYPE_TO_RET.put('L', Opcodes.ARETURN);
    TYPE_TO_RET.put('[', Opcodes.ARETURN);
    TYPE_TO_RET.put('I', Opcodes.IRETURN);
    TYPE_TO_RET.put('Z', Opcodes.IRETURN);
    TYPE_TO_RET.put('B', Opcodes.IRETURN);
    TYPE_TO_RET.put('C', Opcodes.IRETURN);
    TYPE_TO_RET.put('S', Opcodes.IRETURN);
    TYPE_TO_RET.put('J', Opcodes.LRETURN);
    TYPE_TO_RET.put('F', Opcodes.FRETURN);
    TYPE_TO_RET.put('D', Opcodes.DRETURN);
}

public void injectAccessor(ClassNode host, ClassNode fldOwner,
                FieldNode fld, String propName, String retType) {
    if (retType == null) {
        retType = fld.desc;
    }
    MethodNode accessor = new MethodNode(Opcodes.ACC_PUBLIC | Opcodes.ACC_FINAL,
                              "get" + propName, "()" + retType, null, null);
    InsnList insns = new InsnList();
    boolean stateful = (fld.access & Opcodes.ACC_STATIC) == 0;
    if (stateful) {
        if (host == null) {
            host = fldOwner;
        }
        insns.add(new InsnNode(Opcodes.ALOAD_0));
    }
    insns.add(new FieldInsnNode(stateful ? Opcodes.GETFIELD : Opcodes.GETSTATIC,
                      fldOwner.name, fld.name, fld.desc));
    insns.add(new InsnNode(TYPE_TO_RET.get(fld.desc.charAt(0))));
    accessor.instructions = insns;
    host.methods.add(accessor);
}

/*
 * usage: injectAccessor(null, entity_kls, entity_hp_fld, "Hp", null)
 *        injectAccessor(client_kls, game_state_owner, game_state_fld, "GameState", null);
          injectAccessor(client_kls, local_plyr_list_owner, local_plyr_list_fld, "LocalPlayerList", "[Lsupers/jewbot/Player;");
 */