diff --git a/build.gradle b/build.gradle
index e38b2bd..8537b1a 100644
--- a/build.gradle
+++ b/build.gradle
@@ -2,7 +2,6 @@ buildscript {
     ext {
         kotlinVersion = '1.3.71'
         slf4jVersion = '1.7.26'
-
     }
 
     repositories {
@@ -11,10 +10,9 @@ buildscript {
 
     dependencies {
         classpath("org.jetbrains.kotlin:kotlin-gradle-plugin:${kotlinVersion}")
-        classpath "org.jetbrains.dokka:dokka-gradle-plugin:0.9.18"
-        classpath 'com.github.ben-manes:gradle-versions-plugin:0.21.0' // gradle dependencyUpdates -Drevision=release
-        classpath "de.thetaphi:forbiddenapis:2.6"
-        classpath 'com.diffplug.spotless:spotless-plugin-gradle:3.23.1'
+        classpath "org.jetbrains.dokka:dokka-gradle-plugin:0.10.1"
+        classpath 'com.github.ben-manes:gradle-versions-plugin:0.28.0' // gradle dependencyUpdates -Drevision=release
+        classpath 'com.diffplug.spotless:spotless-plugin-gradle:3.28.1'
     }
 }
 
@@ -23,17 +21,8 @@ apply plugin: 'kotlin'
 apply plugin: 'org.jetbrains.dokka'
 apply plugin: 'project-report' // useful for gradle htmlDependencyReport
 apply plugin: 'com.diffplug.gradle.spotless'
-apply plugin: "de.thetaphi.forbiddenapis"
 apply plugin: 'com.github.ben-manes.versions'
 
-forbiddenApis {
-    // https://github.com/policeman-tools/forbidden-apis/wiki/GradleUsage
-    bundledSignatures = ["jdk-unsafe-9", "jdk-deprecated-9", "jdk-non-portable", "jdk-internal-9"]
-    // take out "jdk-system-out"
-    signaturesFiles = files("forbidden_signatures.txt")
-    ignoreFailures = false
-}
-
 // this intentionally breaks the build if you mess up the formatting; pro tip: use Save Actions plugin in intellij and auto format and organize imports on save
 spotless {
     java {
@@ -56,10 +45,12 @@ afterEvaluate {
 }
 
 dokka {
+    configuration {
+        jdkVersion = 8
+        includes = ['src/main/kotlin/io/inbot/eskotlinwrapper/module.md']
+    }
     outputFormat = 'gfm'
-    jdkVersion = 8
     outputDirectory = 'docs'
-    includes = ['src/main/kotlin/io/inbot/eskotlinwrapper/module.md']
 }
 
 tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).all {
@@ -126,7 +117,7 @@ dependencies {
     implementation "org.jetbrains.kotlin:kotlin-stdlib:${kotlinVersion}"
     testImplementation 'io.kotest:kotest-runner-junit5:4.0.2' // for kotest framework
     testImplementation 'io.kotest:kotest-assertions-core-jvm:4.0.2' // for kotest core jvm assertions
-    testCompile 'org.testng:testng:6.13.1'
+    testCompile 'org.testng:testng:7.2.0'
     testCompile 'org.hamcrest:hamcrest-all:1.3'
 
     // kotlintest runner needs this
diff --git a/src/test/java/com/jillesvangurp/geo/GeoGeometryTest.java b/src/test/java/com/jillesvangurp/geo/GeoGeometryTest.java
index 6692ff9..7e1e901 100644
--- a/src/test/java/com/jillesvangurp/geo/GeoGeometryTest.java
+++ b/src/test/java/com/jillesvangurp/geo/GeoGeometryTest.java
@@ -451,14 +451,6 @@ public void shouldCalculateAreaOfMultiPolygon() {
         assertThat(area(multiPolygon), is(2*area(polygon)));
     }
 
-    public void shouldSimplifyLineOnlyOnce() {
-        double[][] line=new double[][] {newyork,moritzPlatz,senefelderPlatz,naturkundeMuseum, buenosaires};
-        double[][] simplified = GeoGeometry.simplifyLine(line, 10000);
-        double[][] superSimplified = GeoGeometry.simplifyLine(simplified,10000);
-        assertThat(simplified.length, lessThan(line.length));
-        assertThat(simplified.length, is(superSimplified.length));
-    }
-
     @DataProvider
     public Object[][] straightLines() {
         return new Object[][] {
diff --git a/src/test/kotlin/com/jillesvangurp/geogeometry/GeoGeometryTest.kt b/src/test/kotlin/com/jillesvangurp/geogeometry/GeoGeometryTest.kt
index 884aafe..1e5c0df 100644
--- a/src/test/kotlin/com/jillesvangurp/geogeometry/GeoGeometryTest.kt
+++ b/src/test/kotlin/com/jillesvangurp/geogeometry/GeoGeometryTest.kt
@@ -1,8 +1,12 @@
 package com.jillesvangurp.geogeometry
 
 import com.jillesvangurp.geo.GeoGeometry
+import com.jillesvangurp.geo.GeoGeometry.Companion.simplifyLine
 import io.kotest.core.spec.style.StringSpec
 import io.kotest.matchers.shouldBe
+import org.hamcrest.CoreMatchers
+import org.hamcrest.MatcherAssert
+import org.hamcrest.Matchers
 
 class GeoGeometryTest : StringSpec() {
     init {
@@ -19,5 +23,6 @@ class GeoGeometryTest : StringSpec() {
             GeoGeometry.linesCross(l1p1, l1p2, l2p1, l2p2) shouldBe false
             GeoGeometry.linesCross(l2p1, l2p2, l1p1, l1p2) shouldBe false
         }
+
     }
 }