add javadoc for test classes

Signed-off-by: Lachlan Roberts <lachlan.p.roberts@gmail.com>

jetty-core/jetty-siwe/src/test/java/org/eclipse/jetty/security/siwe/util/EthereumCredentials.java

@@ -33,6 +33,9 @@ import org.eclipse.jetty.security.siwe.internal.EthereumUtil;
 
 import static org.eclipse.jetty.security.siwe.internal.EthereumUtil.keccak256;
 
+/**
+ * Test utility to generate an ethereum address and use it to sign messages.
+ */
 public class EthereumCredentials
 {
     private final PrivateKey privateKey;

jetty-core/jetty-siwe/src/test/java/org/eclipse/jetty/security/siwe/util/SignInWithEthereumGenerator.java

@@ -16,6 +16,9 @@ package org.eclipse.jetty.security.siwe.util;
 import java.time.LocalDateTime;
 import java.time.format.DateTimeFormatter;
 
+/**
+ * A utility to generate Sign-In with Ethereum message to be used for testing.
+ */
 public class SignInWithEthereumGenerator
 {
     private SignInWithEthereumGenerator()