add a bit more javadoc
diff --git a/src/main/java/org/apache/sling/testing/clients/exceptions/TestingIOException.java b/src/main/java/org/apache/sling/testing/clients/exceptions/TestingIOException.java
index 7597ffc..6f7992e 100644
--- a/src/main/java/org/apache/sling/testing/clients/exceptions/TestingIOException.java
+++ b/src/main/java/org/apache/sling/testing/clients/exceptions/TestingIOException.java
@@ -22,6 +22,10 @@
 import org.apache.sling.testing.clients.ClientException;
 import org.apache.sling.testing.clients.SlingHttpResponse;
 
+/**
+ * Use this exception to indicate any problems with networking (typically manifested as 
+ * IOException).
+ */
 public class TestingIOException extends ClientException {
 
 	public TestingIOException(String message) {
diff --git a/src/main/java/org/apache/sling/testing/clients/exceptions/TestingSetupException.java b/src/main/java/org/apache/sling/testing/clients/exceptions/TestingSetupException.java
index d5f929a..4346837 100644
--- a/src/main/java/org/apache/sling/testing/clients/exceptions/TestingSetupException.java
+++ b/src/main/java/org/apache/sling/testing/clients/exceptions/TestingSetupException.java
@@ -22,6 +22,10 @@
 import org.apache.sling.testing.clients.ClientException;
 import org.apache.sling.testing.clients.SlingHttpResponse;
 
+/**
+ * Use this exception to signal problems in the test setup, e.g. incorrect or missing
+ * parameters.
+ */
 public class TestingSetupException extends ClientException {
 
 	public TestingSetupException(String message) {
diff --git a/src/main/java/org/apache/sling/testing/clients/exceptions/TestingValidationException.java b/src/main/java/org/apache/sling/testing/clients/exceptions/TestingValidationException.java
index ce9e1dd..4a43763 100644
--- a/src/main/java/org/apache/sling/testing/clients/exceptions/TestingValidationException.java
+++ b/src/main/java/org/apache/sling/testing/clients/exceptions/TestingValidationException.java
@@ -22,6 +22,11 @@
 import org.apache.sling.testing.clients.ClientException;
 import org.apache.sling.testing.clients.SlingHttpResponse;
 
+/**
+ * Use this exception to indicate any mismatch between expectations and the actual
+ * test result. This exception typically indicates "real" test failures.
+ *
+ */
 public class TestingValidationException extends ClientException {
 
 	public TestingValidationException(String message) {