diff --git a/src/main/kotlin/net/thauvin/erik/bitly/config/CreateConfig.kt b/src/main/kotlin/net/thauvin/erik/bitly/config/CreateConfig.kt
index e26b17a..3371648 100644
--- a/src/main/kotlin/net/thauvin/erik/bitly/config/CreateConfig.kt
+++ b/src/main/kotlin/net/thauvin/erik/bitly/config/CreateConfig.kt
@@ -52,17 +52,17 @@ class CreateConfig private constructor(
      **/
     @Suppress("unused", "ArrayInDataClass")
     data class Builder(
-        var domain: String = Constants.EMPTY,
-        var title: String = Constants.EMPTY,
-        var group_guid: String = Constants.EMPTY,
-        var tags: Array<String> = emptyArray(),
-        var deeplinks: Array<Map<String, String>> = emptyArray(),
-        var long_url: String = Constants.EMPTY,
-        var toJson: Boolean = false
+        private var domain: String = Constants.EMPTY,
+        private var title: String = Constants.EMPTY,
+        private var group_guid: String = Constants.EMPTY,
+        private var tags: Array<String> = emptyArray(),
+        private var deeplinks: Array<Map<String, String>> = emptyArray(),
+        private var long_url: String = Constants.EMPTY,
+        private var toJson: Boolean = false
     ) {
         fun domain(domain: String) = apply { this.domain = domain }
         fun title(title: String) = apply { this.title = title }
-        fun group_guid(group_guid: String) = apply { this.group_guid = group_guid }
+        fun groupGuid(group_guid: String) = apply { this.group_guid = group_guid }
         fun tags(tags: Array<String>) = apply { this.tags = tags }
         fun deeplinks(deeplinks: Array<Map<String, String>>) = apply { this.deeplinks = deeplinks }
         fun longUrl(long_url: String) = apply { this.long_url = long_url }
diff --git a/src/main/kotlin/net/thauvin/erik/bitly/config/UpdateConfig.kt b/src/main/kotlin/net/thauvin/erik/bitly/config/UpdateConfig.kt
index 0fda24f..556eb38 100644
--- a/src/main/kotlin/net/thauvin/erik/bitly/config/UpdateConfig.kt
+++ b/src/main/kotlin/net/thauvin/erik/bitly/config/UpdateConfig.kt
@@ -59,32 +59,32 @@ class UpdateConfig private constructor(
      **/
     @Suppress("unused", "ArrayInDataClass")
     data class Builder(
-        var bitlink: String = Constants.EMPTY,
-        var references: Map<String, String> = emptyMap(),
-        var archived: Boolean = false,
-        var tags: Array<String> = emptyArray(),
-        var created_at: String = Constants.EMPTY,
-        var title: String = Constants.EMPTY,
-        var deeplinks: Array<Map<String, String>> = emptyArray(),
-        var created_by: String = Constants.EMPTY,
-        var long_url: String = Constants.EMPTY,
-        var client_id: String = Constants.EMPTY,
-        var custom_bitlinks: Array<String> = emptyArray(),
-        var link: String = Constants.EMPTY,
-        var id: String = Constants.EMPTY,
-        var toJson: Boolean = false
+        private var bitlink: String = Constants.EMPTY,
+        private var references: Map<String, String> = emptyMap(),
+        private var archived: Boolean = false,
+        private var tags: Array<String> = emptyArray(),
+        private var created_at: String = Constants.EMPTY,
+        private var title: String = Constants.EMPTY,
+        private var deeplinks: Array<Map<String, String>> = emptyArray(),
+        private var created_by: String = Constants.EMPTY,
+        private var long_url: String = Constants.EMPTY,
+        private var client_id: String = Constants.EMPTY,
+        private var custom_bitlinks: Array<String> = emptyArray(),
+        private var link: String = Constants.EMPTY,
+        private var id: String = Constants.EMPTY,
+        private var toJson: Boolean = false
     ) {
         fun bitlink(bitlink: String) = apply { this.bitlink = bitlink }
         fun references(references: Map<String, String>) = apply { this.references = references }
         fun archived(archived: Boolean) = apply { this.archived = archived }
         fun tags(tags: Array<String>) = apply { this.tags = tags }
-        fun createdAt(created_at: String) = apply { this.created_at = created_at }
+        fun createdAt(createdAt: String) = apply { this.created_at = createdAt }
         fun title(title: String) = apply { this.title = title }
-        fun deeplinks(deeplinks: Array<Map<String, String>>) = apply { this.deeplinks = deeplinks }
-        fun createdBy(created_by: String) = apply { this.created_by = created_by }
-        fun longUrl(long_url: String) = apply { this.long_url = long_url }
-        fun clientId(client_id: String) = apply { this.client_id = client_id }
-        fun customBitlinks(custom_bitlinks: Array<String>) = apply { this.custom_bitlinks = custom_bitlinks }
+        fun deepLinks(deepLinks: Array<Map<String, String>>) = apply { this.deeplinks = deepLinks }
+        fun createdBy(createdBy: String) = apply { this.created_by = createdBy }
+        fun longUrl(longUrl: String) = apply { this.long_url = longUrl }
+        fun clientId(clientId: String) = apply { this.client_id = clientId }
+        fun customBitlinks(customBitlinks: Array<String>) = apply { this.custom_bitlinks = customBitlinks }
         fun link(link: String) = apply { this.link = link }
         fun id(id: String) = apply { this.id = id }
         fun toJson(toJson: Boolean) = apply { this.toJson = toJson }
diff --git a/src/test/kotlin/net/thauvin/erik/bitly/BitlyTest.kt b/src/test/kotlin/net/thauvin/erik/bitly/BitlyTest.kt
index aafde73..3048a94 100644
--- a/src/test/kotlin/net/thauvin/erik/bitly/BitlyTest.kt
+++ b/src/test/kotlin/net/thauvin/erik/bitly/BitlyTest.kt
@@ -33,15 +33,7 @@ package net.thauvin.erik.bitly
 
 import assertk.all
 import assertk.assertThat
-import assertk.assertions.contains
-import assertk.assertions.isEmpty
-import assertk.assertions.isEqualTo
-import assertk.assertions.isFalse
-import assertk.assertions.isNotEqualTo
-import assertk.assertions.isTrue
-import assertk.assertions.matches
-import assertk.assertions.prop
-import assertk.assertions.startsWith
+import assertk.assertions.*
 import net.thauvin.erik.bitly.Utils.isValidUrl
 import net.thauvin.erik.bitly.Utils.removeHttp
 import net.thauvin.erik.bitly.Utils.toEndPoint
@@ -51,11 +43,7 @@ import org.json.JSONObject
 import org.junit.Before
 import java.io.File
 import java.util.logging.Level
-import kotlin.test.Test
-import kotlin.test.assertEquals
-import kotlin.test.assertFailsWith
-import kotlin.test.assertFalse
-import kotlin.test.assertTrue
+import kotlin.test.*
 
 class BitlyTest {
     private val bitly = with(File("local.properties")) {
@@ -219,18 +207,15 @@ class BitlyTest {
 
     @Test
     fun `create bitlink with config`() {
-        var config = CreateConfig.Builder().apply {
-            long_url = longUrl
-        }.build()
+        var config = CreateConfig.Builder().longUrl(longUrl).build()
         assertThat(bitly.bitlinks().create(config), "create(config)")
             .matches("https://\\w+.\\w{2}/\\w{7}".toRegex())
 
-        config = CreateConfig.Builder().apply {
-            domain = "bit.ly"
-            title = "Erik's Blog"
-            tags = arrayOf("erik", "thauvin", "blog", "weblog")
-            long_url = longUrl
-        }.build()
+        config = CreateConfig.Builder()
+            .domain("bit.ly")
+            .title("Erik's Blog")
+            .tags(arrayOf("erik", "thauvin", "blog", "weblog"))
+            .longUrl(longUrl).build()
         assertEquals(
             shortUrl,
             bitly.bitlinks().create(config)
@@ -263,36 +248,34 @@ class BitlyTest {
         bl.update(shortUrl, link = longUrl)
         assertThat(bl.lastCallResponse).prop(CallResponse::isSuccessful).isTrue()
 
-        assertEquals(Constants.FALSE,  bl.update("bit.ly/407GjJU", id = "foo"))
-
+        assertEquals(Constants.FALSE, bl.update("bit.ly/407GjJU", id = "foo"))
     }
 
     @Test
     fun `update bitlink with config`() {
         val bl = bitly.bitlinks()
-        var config = UpdateConfig.Builder().apply {
-            bitlink(shortUrl)
-            title("Erik's Weblog")
-            tags(arrayOf("blog", "weblog"))
-            archived(true)
-        }.build()
+        var config = UpdateConfig.Builder()
+            .bitlink(shortUrl)
+            .title("Erik's Weblog")
+            .tags(arrayOf("blog", "weblog"))
+            .archived(true)
+            .build()
 
         assertEquals(Constants.TRUE, bl.update(config))
 
-        config = UpdateConfig.Builder().apply {
-            bitlink(shortUrl)
-            toJson(true)
-        }.build()
+        config = UpdateConfig.Builder()
+            .bitlink(shortUrl)
+            .toJson(true)
+            .build()
 
         assertThat(bl.update(config), "update(tags)").contains("\"tags\":[]")
 
-        config = UpdateConfig.Builder().apply {
-            bitlink(shortUrl)
-            link(longUrl)
-        }.build()
+        config = UpdateConfig.Builder()
+            .bitlink(shortUrl)
+            .link(longUrl)
+            .build()
 
         assertEquals(Constants.TRUE, bl.update(config))
-
     }
 
     @Test