diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicAPIClientTest.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicAPIClientTest.kt
index 0dd81d46..41d1dd63 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicAPIClientTest.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicAPIClientTest.kt
@@ -23,7 +23,9 @@ import retrofit2.Response
 import java.nio.charset.Charset
 import java.security.MessageDigest
 import java.text.SimpleDateFormat
-import java.util.*
+import java.util.Calendar
+import java.util.Locale
+import java.util.TimeZone
 
 /**
  * Integration test for [SubsonicAPIClient] class.
diff --git a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/rules/MockWebServerRule.kt b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/rules/MockWebServerRule.kt
index 4c88ed26..022457f5 100644
--- a/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/rules/MockWebServerRule.kt
+++ b/subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/rules/MockWebServerRule.kt
@@ -8,11 +8,11 @@ import org.junit.runners.model.Statement
 /**
  * Starts mock web server for test and shut it down after.
  */
-class MockWebServerRule: TestRule {
+class MockWebServerRule : TestRule {
     val mockWebServer = MockWebServer()
 
     override fun apply(base: Statement?, description: Description?): Statement {
-        val ruleStatement = object: Statement() {
+        val ruleStatement = object : Statement() {
             override fun evaluate() {
                 try {
                     mockWebServer.start()
diff --git a/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicAPIVersions.kt b/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicAPIVersions.kt
index b6bb618c..27a8421a 100644
--- a/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicAPIVersions.kt
+++ b/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicAPIVersions.kt
@@ -52,9 +52,9 @@ enum class SubsonicAPIVersions(val subsonicVersions: String, val restApiVersion:
             throw IllegalArgumentException("Unknown api version $apiVersion")
         }
 
-        class SubsonicAPIVersionsDeserializer: JsonDeserializer<SubsonicAPIVersions>() {
-            override fun deserialize(p: JsonParser?, ctxt: DeserializationContext?): SubsonicAPIVersions {
-                if (p!!.currentName != "version") {
+        class SubsonicAPIVersionsDeserializer : JsonDeserializer<SubsonicAPIVersions>() {
+            override fun deserialize(p: JsonParser, ctxt: DeserializationContext?): SubsonicAPIVersions {
+                if (p.currentName != "version") {
                     throw JsonParseException(p, "Not valid token for API version!")
                 }
                 return fromApiVersion(p.text)
diff --git a/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicError.kt b/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicError.kt
index cce83f8a..d6b7160a 100644
--- a/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicError.kt
+++ b/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicError.kt
@@ -25,9 +25,9 @@ enum class SubsonicError(val code: Int) {
                 .filter { it.code == jsonErrorCode }.firstOrNull()
                 ?: throw IllegalArgumentException("Unknown code $jsonErrorCode")
 
-        class SubsonicErrorDeserializer: JsonDeserializer<SubsonicError>() {
-            override fun deserialize(p: JsonParser?, ctxt: DeserializationContext?): SubsonicError {
-                p!!.nextToken() // "code"
+        class SubsonicErrorDeserializer : JsonDeserializer<SubsonicError>() {
+            override fun deserialize(p: JsonParser, ctxt: DeserializationContext?): SubsonicError {
+                p.nextToken() // "code"
                 val error = parseErrorFromJson(p.valueAsInt)
                 p.nextToken() // "message"
                 p.nextToken() // end of error object
diff --git a/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/models/Artist.kt b/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/models/Artist.kt
index b616c753..c1ca8d42 100644
--- a/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/models/Artist.kt
+++ b/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/models/Artist.kt
@@ -1,6 +1,6 @@
 package org.moire.ultrasonic.api.subsonic.models
 
-import java.util.*
+import java.util.Calendar
 
 data class Artist(val id: Long,
                   val name: String,
diff --git a/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/models/MusicDirectory.kt b/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/models/MusicDirectory.kt
index cbe09064..10d0d0eb 100644
--- a/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/models/MusicDirectory.kt
+++ b/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/models/MusicDirectory.kt
@@ -1,7 +1,7 @@
 package org.moire.ultrasonic.api.subsonic.models
 
 import com.fasterxml.jackson.annotation.JsonProperty
-import java.util.*
+import java.util.Calendar
 
 data class MusicDirectory(val id: Long,
                           val name: String,
diff --git a/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/models/MusicDirectoryChild.kt b/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/models/MusicDirectoryChild.kt
index dc7bae18..d4eb331d 100644
--- a/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/models/MusicDirectoryChild.kt
+++ b/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/models/MusicDirectoryChild.kt
@@ -1,6 +1,6 @@
 package org.moire.ultrasonic.api.subsonic.models
 
-import java.util.*
+import java.util.Calendar
 
 data class MusicDirectoryChild(val id: Long, val parent: Long, val isDir: Boolean = false,
                                val title: String = "", val album: String = "",
diff --git a/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/response/LicenseResponse.kt b/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/response/LicenseResponse.kt
index e5bcf81b..5cecbc8e 100644
--- a/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/response/LicenseResponse.kt
+++ b/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/response/LicenseResponse.kt
@@ -7,5 +7,5 @@ import org.moire.ultrasonic.api.subsonic.models.License
 class LicenseResponse(val license: License = License(),
                       status: Status,
                       version: SubsonicAPIVersions,
-                      error: SubsonicError?):
+                      error: SubsonicError?) :
         SubsonicResponse(status, version, error)
\ No newline at end of file
diff --git a/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/response/MusicFoldersResponse.kt b/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/response/MusicFoldersResponse.kt
index 24f91058..5f7bf796 100644
--- a/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/response/MusicFoldersResponse.kt
+++ b/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/response/MusicFoldersResponse.kt
@@ -14,12 +14,12 @@ class MusicFoldersResponse(status: Status,
                            version: SubsonicAPIVersions,
                            error: SubsonicError?,
                            @JsonDeserialize(using = MusicFoldersDeserializer::class)
-                           val musicFolders: List<MusicFolder> = emptyList()):
+                           val musicFolders: List<MusicFolder> = emptyList()) :
         SubsonicResponse(status, version, error) {
     companion object {
-        class MusicFoldersDeserializer(): JsonDeserializer<List<MusicFolder>>() {
-            override fun deserialize(p: JsonParser?, ctxt: DeserializationContext?): List<MusicFolder> {
-                p!!.nextToken()
+        class MusicFoldersDeserializer() : JsonDeserializer<List<MusicFolder>>() {
+            override fun deserialize(p: JsonParser, ctxt: DeserializationContext?): List<MusicFolder> {
+                p.nextToken()
                 if (p.currentName == "musicFolder" && p.nextToken() == JsonToken.START_ARRAY) {
                     val mfJavaType = ctxt!!.typeFactory
                             .constructCollectionType(List::class.java, MusicFolder::class.java)
diff --git a/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/response/SubsonicResponse.kt b/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/response/SubsonicResponse.kt
index 8f15947d..2681ad04 100644
--- a/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/response/SubsonicResponse.kt
+++ b/subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/response/SubsonicResponse.kt
@@ -25,9 +25,9 @@ open class SubsonicResponse(val status: Status,
                     .filter { it.jsonValue == jsonValue }.firstOrNull()
                     ?: throw IllegalArgumentException("Unknown status value: $jsonValue")
 
-            class StatusJsonDeserializer: JsonDeserializer<Status>() {
-                override fun deserialize(p: JsonParser?, ctxt: DeserializationContext?): Status {
-                    if (p!!.currentName != "status") {
+            class StatusJsonDeserializer : JsonDeserializer<Status>() {
+                override fun deserialize(p: JsonParser, ctxt: DeserializationContext?): Status {
+                    if (p.currentName != "status") {
                         throw JsonParseException(p,
                                 "Current token is not status. Current token name ${p.currentName}.")
                     }