[3210] Changes after review:

 - flag => configuration parameter
 - echoClientId test uses ASSERTs rather than EXPECTs

ChangeLog

 XXX.	[func]		tomek
 	b10-dhcp4: Support for sending back client-id (RFC6842) has been
-	added now. Also a flag (echo-client-id) has been added, so it is
-	possible to enable backward compatibility (echo-client-id false).
+	added now. Also a configuration parameter (echo-client-id) has
+	been added, so it is possible to enable backward compatibility
+	("echo-client-id false").
 	(Trac #3210, git abcd)
 
 698.	[bug]		muks

doc/guide/bind10-guide.xml

@@ -4426,8 +4426,8 @@ Dhcp4/subnet4	[]	list	(default)
       that Kea offers. However, in some cases older devices that do
       not support RFC6842 may refuse to accept responses that include
       client-id option. To enable backward compatibility, an optional
-      flag has been introduced. To configure it, use the following
-      commands:</para>
+      configuration parameter has been introduced. To configure it,
+      use the following commands:</para>
 
 <screen>
 &gt; <userinput>config add Dhcp4/echo-client-id</userinput>

src/bin/dhcp4/tests/config_parser_unittest.cc

@@ -583,15 +583,15 @@ TEST_F(Dhcp4ParserTest, echoClientId) {
     ElementPtr json_true = Element::fromJSON(config_true);
 
     // Let's check the default. It should be true
-    EXPECT_TRUE(CfgMgr::instance().echoClientId());
+    ASSERT_TRUE(CfgMgr::instance().echoClientId());
 
     // Now check that "false" configuration is really applied.
     EXPECT_NO_THROW(status = configureDhcp4Server(*srv_, json_false));
-    EXPECT_FALSE(CfgMgr::instance().echoClientId());
+    ASSERT_FALSE(CfgMgr::instance().echoClientId());
 
     // Now check that "true" configuration is really applied.
     EXPECT_NO_THROW(status = configureDhcp4Server(*srv_, json_true));
-    EXPECT_TRUE(CfgMgr::instance().echoClientId());
+    ASSERT_TRUE(CfgMgr::instance().echoClientId());
 
     // In any case revert back to the default value (true)
     CfgMgr::instance().echoClientId(true);