diff --git a/src/main/kotlin/dev/usbharu/activitystreams/impl/model/activity/CreateImpl.kt b/src/main/kotlin/dev/usbharu/activitystreams/impl/model/activity/CreateImpl.kt
index 65c59a1..c09b879 100644
--- a/src/main/kotlin/dev/usbharu/activitystreams/impl/model/activity/CreateImpl.kt
+++ b/src/main/kotlin/dev/usbharu/activitystreams/impl/model/activity/CreateImpl.kt
@@ -1,6 +1,7 @@
 package dev.usbharu.activitystreams.impl.model.activity
 
 import dev.usbharu.activitystreams.model.ImageOrLink
+import dev.usbharu.activitystreams.model.JsonLdWrapper
 import dev.usbharu.activitystreams.model.ObjectOrLink
 import dev.usbharu.activitystreams.model.UriOrLink
 import dev.usbharu.activitystreams.model.activity.Create
@@ -12,39 +13,40 @@ import java.time.Duration
 import java.time.OffsetDateTime
 
 class CreateImpl(
-    override var type: List<URI>,
-    override var `object`: ObjectOrLink?,
-    override var actor: List<ObjectOrLink>,
-    override var target: List<ObjectOrLink>,
-    override var result: ObjectOrLink?,
-    override var origin: ObjectOrLink?,
-    override var instrument: ObjectOrLink?,
-    override var attachment: List<ObjectOrLink>,
-    override var attributedTo: List<ObjectOrLink>,
-    override var audience: List<ObjectOrLink>,
-    override var content: LangString?,
-    override var context: List<ObjectOrLink>,
-    override var name: LangString?,
-    override var endTime: OffsetDateTime?,
-    override var generator: List<ObjectOrLink>,
-    override var icon: List<ImageOrLink>,
-    override var image: List<ImageOrLink>,
-    override var inReplyTo: List<ObjectOrLink>,
-    override var location: ObjectOrLink?,
-    override var preview: ObjectOrLink?,
-    override var published: OffsetDateTime?,
-    override var replies: Collection?,
-    override var startTime: OffsetDateTime?,
-    override var summary: LangString?,
-    override var tag: List<ObjectOrLink>,
-    override var updated: OffsetDateTime?,
-    override var url: List<UriOrLink>,
-    override var to: List<ObjectOrLink>,
-    override var bto: List<ObjectOrLink>,
-    override var cc: List<ObjectOrLink>,
-    override var bcc: List<ObjectOrLink>,
-    override var mediaType: MimeMediaType?,
-    override var duration: Duration?,
-    override var id: URI?,
-    override var source: ObjectOrLink?
+    override var type: List<URI> = emptyList(),
+    override var `object`: ObjectOrLink? = null,
+    override var actor: List<ObjectOrLink> = emptyList(),
+    override var target: List<ObjectOrLink> = emptyList(),
+    override var result: ObjectOrLink? = null,
+    override var origin: ObjectOrLink? = null,
+    override var instrument: ObjectOrLink? = null,
+    override var attachment: List<ObjectOrLink> = emptyList(),
+    override var attributedTo: List<ObjectOrLink> = emptyList(),
+    override var audience: List<ObjectOrLink> = emptyList(),
+    override var content: LangString? = null,
+    override var context: List<ObjectOrLink> = emptyList(),
+    override var name: LangString? = null,
+    override var endTime: JsonLdWrapper<OffsetDateTime>? = null,
+    override var generator: List<ObjectOrLink> = emptyList(),
+    override var icon: List<ImageOrLink> = emptyList(),
+    override var image: List<ImageOrLink> = emptyList(),
+    override var inReplyTo: List<ObjectOrLink> = emptyList(),
+    override var location: ObjectOrLink? = null,
+    override var preview: ObjectOrLink? = null,
+    override var published: JsonLdWrapper<OffsetDateTime>? = null,
+    override var replies: Collection? = null,
+    override var startTime: JsonLdWrapper<OffsetDateTime>? = null,
+    override var summary: LangString? = null,
+    override var tag: List<ObjectOrLink> = emptyList(),
+    override var updated: JsonLdWrapper<OffsetDateTime>? = null,
+    override var url: List<UriOrLink> = emptyList(),
+    override var to: List<ObjectOrLink> = emptyList(),
+    override var bto: List<ObjectOrLink> = emptyList(),
+    override var cc: List<ObjectOrLink> = emptyList(),
+    override var bcc: List<ObjectOrLink> = emptyList(),
+    override var mediaType: MimeMediaType? = null,
+    override var duration: JsonLdWrapper<Duration>? = null,
+    override var id: URI? = null,
+    override var source: ObjectOrLink? = null,
+    override var value: Any? = null,
 ) : Create
\ No newline at end of file
diff --git a/src/main/kotlin/dev/usbharu/activitystreams/impl/model/actor/PersonImpl.kt b/src/main/kotlin/dev/usbharu/activitystreams/impl/model/actor/PersonImpl.kt
index c9fa848..bc52652 100644
--- a/src/main/kotlin/dev/usbharu/activitystreams/impl/model/actor/PersonImpl.kt
+++ b/src/main/kotlin/dev/usbharu/activitystreams/impl/model/actor/PersonImpl.kt
@@ -1,6 +1,7 @@
 package dev.usbharu.activitystreams.impl.model.actor
 
 import dev.usbharu.activitystreams.model.ImageOrLink
+import dev.usbharu.activitystreams.model.JsonLdWrapper
 import dev.usbharu.activitystreams.model.ObjectOrLink
 import dev.usbharu.activitystreams.model.UriOrLink
 import dev.usbharu.activitystreams.model.actor.Person
@@ -12,50 +13,51 @@ import java.time.Duration
 import java.time.OffsetDateTime
 
 class PersonImpl(
-    override var type: List<URI>,
-    override var attachment: List<ObjectOrLink>,
-    override var attributedTo: List<ObjectOrLink>,
-    override var audience: List<ObjectOrLink>,
-    override var content: LangString?,
-    override var context: List<ObjectOrLink>,
-    override var name: LangString?,
-    override var endTime: OffsetDateTime?,
-    override var generator: List<ObjectOrLink>,
-    override var icon: List<ImageOrLink>,
-    override var image: List<ImageOrLink>,
-    override var inReplyTo: List<ObjectOrLink>,
-    override var location: ObjectOrLink?,
-    override var preview: ObjectOrLink?,
-    override var published: OffsetDateTime?,
-    override var replies: Collection?,
-    override var startTime: OffsetDateTime?,
-    override var summary: LangString?,
-    override var tag: List<ObjectOrLink>,
-    override var updated: OffsetDateTime?,
-    override var url: List<UriOrLink>,
-    override var to: List<ObjectOrLink>,
-    override var bto: List<ObjectOrLink>,
-    override var cc: List<ObjectOrLink>,
-    override var bcc: List<ObjectOrLink>,
-    override var mediaType: MimeMediaType?,
-    override var duration: Duration?,
-    override var id: URI?,
-    override var source: ObjectOrLink?,
-    override var endpoints: List<URI>,
-    override var following: URI?,
-    override var followers: URI?,
-    override var inbox: URI?,
-    override var outbox: URI?,
-    override var liked: URI?,
-    override var shared: URI?,
-    override var likes: URI?,
-    override var oauthAuthorizationEndpoint: URI?,
-    override var oauthTokenEndpoint: URI?,
-    override var preferredUsername: String?,
-    override var provideClientKey: URI?,
-    override var proxyUrl: URI?,
-    override var sharedInbox: URI?,
-    override var signClientKey: URI?,
-    override var streams: URI?,
-    override var alsoKnownAs: List<URI>
+    override var type: List<URI> = emptyList(),
+    override var attachment: List<ObjectOrLink> = emptyList(),
+    override var attributedTo: List<ObjectOrLink> = emptyList(),
+    override var audience: List<ObjectOrLink> = emptyList(),
+    override var content: LangString? = null,
+    override var context: List<ObjectOrLink> = emptyList(),
+    override var name: LangString? = null,
+    override var endTime: JsonLdWrapper<OffsetDateTime>? = null,
+    override var generator: List<ObjectOrLink> = emptyList(),
+    override var icon: List<ImageOrLink> = emptyList(),
+    override var image: List<ImageOrLink> = emptyList(),
+    override var inReplyTo: List<ObjectOrLink> = emptyList(),
+    override var location: ObjectOrLink? = null,
+    override var preview: ObjectOrLink? = null,
+    override var published: JsonLdWrapper<OffsetDateTime>? = null,
+    override var replies: Collection? = null,
+    override var startTime: JsonLdWrapper<OffsetDateTime>? = null,
+    override var summary: LangString? = null,
+    override var tag: List<ObjectOrLink> = emptyList(),
+    override var updated: JsonLdWrapper<OffsetDateTime>? = null,
+    override var url: List<UriOrLink> = emptyList(),
+    override var to: List<ObjectOrLink> = emptyList(),
+    override var bto: List<ObjectOrLink> = emptyList(),
+    override var cc: List<ObjectOrLink> = emptyList(),
+    override var bcc: List<ObjectOrLink> = emptyList(),
+    override var mediaType: MimeMediaType? = null,
+    override var duration: JsonLdWrapper<Duration>? = null,
+    override var id: URI? = null,
+    override var source: ObjectOrLink? = null,
+    override var endpoints: List<URI> = emptyList(),
+    override var following: URI? = null,
+    override var followers: URI? = null,
+    override var inbox: URI? = null,
+    override var outbox: URI? = null,
+    override var liked: URI? = null,
+    override var shared: URI? = null,
+    override var likes: URI? = null,
+    override var oauthAuthorizationEndpoint: URI? = null,
+    override var oauthTokenEndpoint: URI? = null,
+    override var preferredUsername: String? = null,
+    override var provideClientKey: URI? = null,
+    override var proxyUrl: URI? = null,
+    override var sharedInbox: URI? = null,
+    override var signClientKey: URI? = null,
+    override var streams: URI? = null,
+    override var alsoKnownAs: List<URI> = emptyList(),
+    override var value: Any? = null
 ) : Person
\ No newline at end of file
diff --git a/src/main/kotlin/dev/usbharu/activitystreams/impl/type/TypeFactory.kt b/src/main/kotlin/dev/usbharu/activitystreams/impl/type/TypeFactory.kt
index fc3554e..0dd2cf8 100644
--- a/src/main/kotlin/dev/usbharu/activitystreams/impl/type/TypeFactory.kt
+++ b/src/main/kotlin/dev/usbharu/activitystreams/impl/type/TypeFactory.kt
@@ -1,10 +1,16 @@
 package dev.usbharu.activitystreams.impl.type
 
+import dev.usbharu.activitystreams.impl.model.activity.CreateImpl
 import dev.usbharu.activitystreams.model.JsonLd
 import java.net.URI
 
 class TypeFactory {
-    fun factory(uri: String): List<JsonLd> {
 
+    val map = mutableMapOf<URI, () -> JsonLd>(
+        URI.create("https://www.w3.org/ns/activitystreams#Create") to { CreateImpl() }
+    )
+
+    fun factory(uri: URI): JsonLd? {
+        return map[uri]?.invoke()
     }
 }
\ No newline at end of file
diff --git a/src/main/kotlin/dev/usbharu/activitystreams/model/JsonLd.kt b/src/main/kotlin/dev/usbharu/activitystreams/model/JsonLd.kt
index ac7ed70..c7464fb 100644
--- a/src/main/kotlin/dev/usbharu/activitystreams/model/JsonLd.kt
+++ b/src/main/kotlin/dev/usbharu/activitystreams/model/JsonLd.kt
@@ -5,5 +5,5 @@ import java.net.URI
 interface JsonLd {
     var type: List<URI>
     var id: URI?
-    var value: Any
+    var value: Any?
 }
\ No newline at end of file
diff --git a/src/main/kotlin/dev/usbharu/activitystreams/model/JsonLdWrapper.kt b/src/main/kotlin/dev/usbharu/activitystreams/model/JsonLdWrapper.kt
new file mode 100644
index 0000000..21f9dc4
--- /dev/null
+++ b/src/main/kotlin/dev/usbharu/activitystreams/model/JsonLdWrapper.kt
@@ -0,0 +1,7 @@
+package dev.usbharu.activitystreams.model
+
+import java.net.URI
+
+class JsonLdWrapper<T>(override var type: List<URI>, override var id: URI?, value: T?) : JsonLd {
+    override var value: Any? = value
+}
\ No newline at end of file
diff --git a/src/main/kotlin/dev/usbharu/activitystreams/model/core/Object.kt b/src/main/kotlin/dev/usbharu/activitystreams/model/core/Object.kt
index 252e879..1bcfc2e 100644
--- a/src/main/kotlin/dev/usbharu/activitystreams/model/core/Object.kt
+++ b/src/main/kotlin/dev/usbharu/activitystreams/model/core/Object.kt
@@ -1,11 +1,9 @@
 package dev.usbharu.activitystreams.model.core
 
-import dev.usbharu.activitystreams.model.ImageOrLink
-import dev.usbharu.activitystreams.model.JsonLd
-import dev.usbharu.activitystreams.model.ObjectOrLink
-import dev.usbharu.activitystreams.model.UriOrLink
+import dev.usbharu.activitystreams.model.*
 import dev.usbharu.activitystreams.model.other.LangString
 import dev.usbharu.activitystreams.model.other.MimeMediaType
+import java.net.URI
 import java.time.Duration
 import java.time.OffsetDateTime
 
@@ -16,25 +14,25 @@ interface Object : ObjectOrLink, JsonLd {
     var content: LangString?
     var context: List<ObjectOrLink>
     var name: LangString?
-    var endTime: OffsetDateTime?
+    var endTime: JsonLdWrapper<OffsetDateTime>?
     var generator: List<ObjectOrLink>
     var icon: List<ImageOrLink>
     var image: List<ImageOrLink>
     var inReplyTo: List<ObjectOrLink>
     var location: ObjectOrLink?
     var preview: ObjectOrLink?
-    var published: OffsetDateTime?
+    var published: JsonLdWrapper<OffsetDateTime>?
     var replies: Collection?
-    var startTime: OffsetDateTime?
+    var startTime: JsonLdWrapper<OffsetDateTime>?
     var summary: LangString?
     var tag: List<ObjectOrLink>
-    var updated: OffsetDateTime?
+    var updated: JsonLdWrapper<OffsetDateTime>?
     var url: List<UriOrLink>
     var to: List<ObjectOrLink>
     var bto: List<ObjectOrLink>
     var cc: List<ObjectOrLink>
     var bcc: List<ObjectOrLink>
     var mediaType: MimeMediaType?
-    var duration: Duration?
+    var duration: JsonLdWrapper<Duration>?
     var source: ObjectOrLink?
 }
\ No newline at end of file
diff --git a/src/main/kotlin/dev/usbharu/activitystreams/model/other/LangString.kt b/src/main/kotlin/dev/usbharu/activitystreams/model/other/LangString.kt
index 1a0b9a7..568e2cd 100644
--- a/src/main/kotlin/dev/usbharu/activitystreams/model/other/LangString.kt
+++ b/src/main/kotlin/dev/usbharu/activitystreams/model/other/LangString.kt
@@ -1,8 +1,9 @@
 package dev.usbharu.activitystreams.model.other
 
+import dev.usbharu.activitystreams.model.JsonLd
 import java.util.Locale
 
-interface LangString : Map<String, String> {
+interface LangString : Map<String, String>,JsonLd {
     fun getValue(): String?
     fun getValueByLanguageTag(locale: Locale): String?
 }
\ No newline at end of file
diff --git a/src/main/kotlin/dev/usbharu/activitystreams/model/other/MimeMediaType.kt b/src/main/kotlin/dev/usbharu/activitystreams/model/other/MimeMediaType.kt
index fbf8ebb..155a011 100644
--- a/src/main/kotlin/dev/usbharu/activitystreams/model/other/MimeMediaType.kt
+++ b/src/main/kotlin/dev/usbharu/activitystreams/model/other/MimeMediaType.kt
@@ -1,4 +1,6 @@
 package dev.usbharu.activitystreams.model.other
 
-interface MimeMediaType {
+import dev.usbharu.activitystreams.model.JsonLd
+
+interface MimeMediaType : JsonLd {
 }
\ No newline at end of file