Added missing documentation for public classes (#621)

* added missing dokumentation for public classes

* Wrong documentation package corrected

* Update jplag.endtoend-testing/src/main/java/de/jplag/endtoend/helper/JsonHelper.java

Co-authored-by: Dominik Fuchß <develop@fuchss.org>

Co-authored-by: Dominik Fuchß <develop@fuchss.org>

jplag.endtoend-testing/src/main/java/de/jplag/endtoend/helper/JsonHelper.java

@@ -12,6 +12,11 @@ import com.fasterxml.jackson.databind.ObjectWriter;
 import de.jplag.endtoend.constants.TestDirectoryConstants;
 import de.jplag.endtoend.model.ResultDescription;
 
+/**
+ * Helper class for serialization and deserialization of the used json format into the correct record classes. The
+ * serialization/deserialization is enabled using the Jackson library. The record classes used can be found at
+ * {@link de.jplag.endtoend.model}.
+ */
 public class JsonHelper {
     /**
      * private constructor to prevent instantiation

jplag.endtoend-testing/src/main/java/de/jplag/endtoend/helper/TestSuiteHelper.java

@@ -14,6 +14,9 @@ import de.jplag.JPlagComparison;
 import de.jplag.Submission;
 import de.jplag.endtoend.constants.TestDirectoryConstants;
 
+/**
+ * Helper class to perform all necessary additional functions for the endToEnd tests.
+ */
 public class TestSuiteHelper {
 
     /**