diff --git a/build.gradle b/build.gradle
index 3d91a94..297866c 100644
--- a/build.gradle
+++ b/build.gradle
@@ -1,7 +1,7 @@
 plugins {
     id 'java'
-    id 'org.springframework.boot' version '3.2.5'
-    id 'io.spring.dependency-management' version '1.1.4'
+    id 'org.springframework.boot' version '2.6.7'
+    id 'io.spring.dependency-management' version '1.1.0'
     id 'war'
 }
 
@@ -9,7 +9,7 @@
 version = '0.0.1-SNAPSHOT'
 
 java {
-    sourceCompatibility = '21'
+    sourceCompatibility = '17'
 }
 
 repositories {
diff --git a/src/main/java/org/ntlab/citrusserver/resources/AccountsRest.java b/src/main/java/org/ntlab/citrusserver/resources/AccountsRest.java
index a305d5a..c1efb1d 100644
--- a/src/main/java/org/ntlab/citrusserver/resources/AccountsRest.java
+++ b/src/main/java/org/ntlab/citrusserver/resources/AccountsRest.java
@@ -1,7 +1,7 @@
 package org.ntlab.citrusserver.resources;
-import jakarta.ws.rs.*;
-import jakarta.ws.rs.core.MediaType;
-import jakarta.ws.rs.core.Response;
+import javax.ws.rs.*;
+import javax.ws.rs.core.MediaType;
+import javax.ws.rs.core.Response;
 import org.ntlab.citrusserver.entities.Account;
 import org.ntlab.citrusserver.repositories.AccountManager;
 import org.ntlab.citrusserver.repositories.BookManager;
@@ -17,7 +17,6 @@
 
 @Path("/accounts")
 @Component //accountRestのインスタンスを一個作る
-
 public class AccountsRest {
     private final AccountManager accountManager; //finalは書き換えられない
     private final BookManager bookManager;
diff --git a/src/main/java/org/ntlab/citrusserver/resources/BooksRest.java b/src/main/java/org/ntlab/citrusserver/resources/BooksRest.java
index 6e8982c..20fbe78 100644
--- a/src/main/java/org/ntlab/citrusserver/resources/BooksRest.java
+++ b/src/main/java/org/ntlab/citrusserver/resources/BooksRest.java
@@ -1,8 +1,8 @@
 package org.ntlab.citrusserver.resources;
 
-import jakarta.ws.rs.*;
-import jakarta.ws.rs.core.MediaType;
-import jakarta.ws.rs.core.Response;
+import javax.ws.rs.*;
+import javax.ws.rs.core.MediaType;
+import javax.ws.rs.core.Response;
 import org.ntlab.citrusserver.entities.Book;
 import org.ntlab.citrusserver.repositories.AccountManager;
 import org.ntlab.citrusserver.repositories.BookManager;
diff --git a/src/main/java/org/ntlab/citrusserver/resources/FavoritedRest.java b/src/main/java/org/ntlab/citrusserver/resources/FavoritedRest.java
index 621ebf0..76e5b7d 100644
--- a/src/main/java/org/ntlab/citrusserver/resources/FavoritedRest.java
+++ b/src/main/java/org/ntlab/citrusserver/resources/FavoritedRest.java
@@ -1,7 +1,7 @@
 package org.ntlab.citrusserver.resources;
 
-import jakarta.ws.rs.*;
-import jakarta.ws.rs.core.MediaType;
+import javax.ws.rs.*;
+import javax.ws.rs.core.MediaType;
 import org.ntlab.citrusserver.repositories.AccountManager;
 import org.ntlab.citrusserver.repositories.FavoriteManager;
 import org.springframework.beans.factory.annotation.Autowired;
diff --git a/src/main/java/org/ntlab/citrusserver/resources/FavoritesRest.java b/src/main/java/org/ntlab/citrusserver/resources/FavoritesRest.java
index c90074a..43d30db 100644
--- a/src/main/java/org/ntlab/citrusserver/resources/FavoritesRest.java
+++ b/src/main/java/org/ntlab/citrusserver/resources/FavoritesRest.java
@@ -1,9 +1,9 @@
 package org.ntlab.citrusserver.resources;
 
 
-import jakarta.ws.rs.*;
-import jakarta.ws.rs.core.MediaType;
-import jakarta.ws.rs.core.Response;
+import javax.ws.rs.*;
+import javax.ws.rs.core.MediaType;
+import javax.ws.rs.core.Response;
 import org.ntlab.citrusserver.repositories.AccountManager;
 import org.ntlab.citrusserver.repositories.FavoriteManager;
 import org.springframework.beans.factory.annotation.Autowired;
diff --git a/src/main/java/org/ntlab/citrusserver/resources/HelloWorldRest.java b/src/main/java/org/ntlab/citrusserver/resources/HelloWorldRest.java
index d612750..2e97c7f 100644
--- a/src/main/java/org/ntlab/citrusserver/resources/HelloWorldRest.java
+++ b/src/main/java/org/ntlab/citrusserver/resources/HelloWorldRest.java
@@ -1,7 +1,7 @@
 package org.ntlab.citrusserver.resources;
 
-import jakarta.ws.rs.*;
-import jakarta.ws.rs.core.MediaType;
+import javax.ws.rs.*;
+import javax.ws.rs.core.MediaType;
 import org.springframework.stereotype.Component;
 
 @Path("/helloworld")
diff --git a/src/main/java/org/ntlab/citrusserver/resources/PublicBooksRest.java b/src/main/java/org/ntlab/citrusserver/resources/PublicBooksRest.java
index 192022f..4820154 100644
--- a/src/main/java/org/ntlab/citrusserver/resources/PublicBooksRest.java
+++ b/src/main/java/org/ntlab/citrusserver/resources/PublicBooksRest.java
@@ -1,7 +1,7 @@
 package org.ntlab.citrusserver.resources;
 
-import jakarta.ws.rs.*;
-import jakarta.ws.rs.core.MediaType;
+import javax.ws.rs.*;
+import javax.ws.rs.core.MediaType;
 import org.ntlab.citrusserver.entities.Book;
 import org.ntlab.citrusserver.repositories.PublicBookManager;
 import org.springframework.beans.factory.annotation.Autowired;
diff --git a/src/main/java/org/ntlab/citrusserver/resources/ScheduleRest.java b/src/main/java/org/ntlab/citrusserver/resources/ScheduleRest.java
index 5d08c8d..f880c8a 100644
--- a/src/main/java/org/ntlab/citrusserver/resources/ScheduleRest.java
+++ b/src/main/java/org/ntlab/citrusserver/resources/ScheduleRest.java
@@ -1,11 +1,11 @@
 package org.ntlab.citrusserver.resources;
 
-import jakarta.ws.rs.core.Response;
+import javax.ws.rs.core.Response;
 import org.ntlab.citrusserver.entities.Schedule;
 import org.ntlab.citrusserver.repositories.AccountManager;
 import org.ntlab.citrusserver.repositories.ScheduleManager;
-import jakarta.ws.rs.*;
-import jakarta.ws.rs.core.MediaType;
+import javax.ws.rs.*;
+import javax.ws.rs.core.MediaType;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Component;
 
diff --git a/src/main/java/org/ntlab/citrusserver/resources/TodoRest.java b/src/main/java/org/ntlab/citrusserver/resources/TodoRest.java
index 22c1f7d..b94a8bc 100644
--- a/src/main/java/org/ntlab/citrusserver/resources/TodoRest.java
+++ b/src/main/java/org/ntlab/citrusserver/resources/TodoRest.java
@@ -1,8 +1,8 @@
 package org.ntlab.citrusserver.resources;
 
-import jakarta.ws.rs.*;
-import jakarta.ws.rs.core.MediaType;
-import jakarta.ws.rs.core.Response;
+import javax.ws.rs.*;
+import javax.ws.rs.core.MediaType;
+import javax.ws.rs.core.Response;
 import org.apache.coyote.http11.upgrade.UpgradeServletOutputStream;
 import org.ntlab.citrusserver.entities.Todo;
 import org.ntlab.citrusserver.repositories.AccountManager;