diff --git a/base/pom.xml b/base/pom.xml
index a571def0..423a38d3 100644
--- a/base/pom.xml
+++ b/base/pom.xml
@@ -26,6 +26,12 @@
         <dependency><groupId>org.junit.jupiter</groupId><artifactId>junit-jupiter</artifactId><scope>test</scope></dependency>
         <dependency><groupId>org.mockito</groupId><artifactId>mockito-core</artifactId><scope>test</scope></dependency>
         <dependency><groupId>org.mockito</groupId><artifactId>mockito-junit-jupiter</artifactId><scope>test</scope></dependency>
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+            <version>31.1-jre</version>
+        </dependency>
+
     </dependencies>
 
     <build>
diff --git a/base/src/main/java/com/calpano/graphinout/base/gio/GioDocument.java b/base/src/main/java/com/calpano/graphinout/base/gio/GioDocument.java
index 234c041b..95f07dcb 100644
--- a/base/src/main/java/com/calpano/graphinout/base/gio/GioDocument.java
+++ b/base/src/main/java/com/calpano/graphinout/base/gio/GioDocument.java
@@ -1,6 +1,7 @@
 package com.calpano.graphinout.base.gio;
 
 import lombok.Data;
+import lombok.EqualsAndHashCode;
 import lombok.experimental.SuperBuilder;
 
 import java.util.List;
@@ -9,6 +10,7 @@
 /**
  * The root document of a Gio model graph stream.
  */
+@EqualsAndHashCode(callSuper = true)
 @Data
 @SuperBuilder
 public class GioDocument extends GioElementWithDescription {
diff --git a/base/src/main/java/com/calpano/graphinout/base/gio/ValidatingGioWriter.java b/base/src/main/java/com/calpano/graphinout/base/gio/ValidatingGioWriter.java
index 1189ca6c..ec5fcf3c 100644
--- a/base/src/main/java/com/calpano/graphinout/base/gio/ValidatingGioWriter.java
+++ b/base/src/main/java/com/calpano/graphinout/base/gio/ValidatingGioWriter.java
@@ -1,5 +1,6 @@
 package com.calpano.graphinout.base.gio;
 
+import com.google.common.collect.Sets;
 import lombok.RequiredArgsConstructor;
 
 import javax.annotation.Nullable;
@@ -39,7 +40,7 @@ public void endEdge() throws IOException {
     @Override
     public void endGraph(@Nullable URL locator) throws IOException {
         if (!nodesIds.containsAll(endpointsNode))
-            throw new IllegalStateException("All GioEdge endpoints should refer to an existing GioNode ID.");
+            throw new IllegalStateException("All GioEdge endpoints should refer to an existing GioNode ID. Missing: " + Sets.difference(endpointsNode,nodesIds));
         if (!nodePortName.isEmpty()) {
             List<String> missingPorts = new ArrayList<>();
             for (String port : endpointsPort) {
diff --git a/engine/pom.xml b/engine/pom.xml
index 5f39150f..a45d9dfe 100644
--- a/engine/pom.xml
+++ b/engine/pom.xml
@@ -18,31 +18,12 @@
             <groupId>org.projectlombok</groupId>
             <artifactId>lombok</artifactId>
         </dependency>
-        <dependency>
-            <groupId>com.calpano.graphinout</groupId>
-            <artifactId>base</artifactId>
-            <version>1.0-SNAPSHOT</version>
-        </dependency>
-        <dependency>
-            <groupId>com.calpano.graphinout</groupId>
-            <artifactId>reader-tgf</artifactId>
-            <version>1.0-SNAPSHOT</version>
-        </dependency>
-        <dependency>
-            <groupId>com.calpano.graphinout</groupId>
-            <artifactId>reader-jgrapht</artifactId>
-            <version>1.0-SNAPSHOT</version>
-        </dependency>
-        <dependency>
-            <groupId>com.calpano.graphinout</groupId>
-            <artifactId>reader-graphml</artifactId>
-            <version>1.0-SNAPSHOT</version>
-        </dependency>
-        <dependency>
-            <groupId>com.calpano.graphinout</groupId>
-            <artifactId>reader-json</artifactId>
-            <version>1.0-SNAPSHOT</version>
-        </dependency>
+        <dependency><groupId>com.calpano.graphinout</groupId><artifactId>base</artifactId><version>1.0-SNAPSHOT</version></dependency>
+        <dependency><groupId>com.calpano.graphinout</groupId><artifactId>reader-tgf</artifactId><version>1.0-SNAPSHOT</version></dependency>
+        <dependency><groupId>com.calpano.graphinout</groupId><artifactId>reader-jgrapht</artifactId><version>1.0-SNAPSHOT</version></dependency>
+        <dependency><groupId>com.calpano.graphinout</groupId><artifactId>reader-graphml</artifactId><version>1.0-SNAPSHOT</version></dependency>
+        <dependency><groupId>com.calpano.graphinout</groupId><artifactId>reader-json</artifactId><version>1.0-SNAPSHOT</version></dependency>
+        <dependency><groupId>com.calpano.graphinout</groupId><artifactId>reader-tripletext</artifactId><version>1.0-SNAPSHOT</version></dependency>
         <!-- test -->
         <dependency><groupId>org.junit.jupiter</groupId><artifactId>junit-jupiter</artifactId><scope>test</scope></dependency>
         <dependency><groupId>org.mockito</groupId><artifactId>mockito-core</artifactId><scope>test</scope></dependency>
@@ -55,30 +36,11 @@
             <classifier>tests</classifier>
             <scope>test</scope>
         </dependency>
-        <dependency>
-            <groupId>com.calpano.graphinout</groupId>
-            <artifactId>reader-tgf</artifactId>
-            <version>1.0-SNAPSHOT</version>
-            <type>test-jar</type>
-            <classifier>tests</classifier>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>com.calpano.graphinout</groupId>
-            <artifactId>reader-jgrapht</artifactId>
-            <version>1.0-SNAPSHOT</version>
-            <type>test-jar</type>
-            <classifier>tests</classifier>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>com.calpano.graphinout</groupId>
-            <artifactId>reader-graphml</artifactId>
-            <version>1.0-SNAPSHOT</version>
-            <type>test-jar</type>
-            <classifier>tests</classifier>
-            <scope>test</scope>
-        </dependency>
+        <!-- depend on all reader projects you want to test -->
+        <dependency><groupId>com.calpano.graphinout</groupId><artifactId>reader-tgf</artifactId><version>1.0-SNAPSHOT</version><type>test-jar</type><classifier>tests</classifier><scope>test</scope></dependency>
+        <dependency><groupId>com.calpano.graphinout</groupId><artifactId>reader-jgrapht</artifactId><version>1.0-SNAPSHOT</version><type>test-jar</type><classifier>tests</classifier><scope>test</scope></dependency>
+        <dependency><groupId>com.calpano.graphinout</groupId><artifactId>reader-graphml</artifactId><version>1.0-SNAPSHOT</version><type>test-jar</type><classifier>tests</classifier><scope>test</scope></dependency>
+        <dependency><groupId>com.calpano.graphinout</groupId><artifactId>reader-tripletext</artifactId><version>1.0-SNAPSHOT</version><type>test-jar</type><classifier>tests</classifier><scope>test</scope></dependency>
 
     </dependencies>
 
diff --git a/engine/src/test/java/com/calpano/graphinout/engine/GioEngineCoreTest.java b/engine/src/test/java/com/calpano/graphinout/engine/GioEngineCoreTest.java
index d646e046..6446c719 100644
--- a/engine/src/test/java/com/calpano/graphinout/engine/GioEngineCoreTest.java
+++ b/engine/src/test/java/com/calpano/graphinout/engine/GioEngineCoreTest.java
@@ -45,7 +45,7 @@ static void beforeAll() {
     @Test
     void test() {
         // find all resources
-        ReaderTests.getAllTestResourceFilePaths().forEach(r -> testResource(r));
+        ReaderTests.getAllTestResourceFilePaths().forEach(this::testResource);
 
 
 //        byte[] graphmlBytes1;