Break SessionSource out of SessionMetadata and rename it EppRequestSource.

The "SessionSource" has nothing to do with sessions (and it's often
used in sessionless contexts). What it does indicate is the endpoint
used to make the request.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=125295224

java/google/registry/flows/FlowRunner.java

@@ -44,30 +44,33 @@ public class FlowRunner {
   private final EppInput eppInput;
   private final Trid trid;
   private final SessionMetadata sessionMetadata;
+  private final TransportCredentials credentials;
+  private final EppRequestSource eppRequestSource;
   private final boolean isDryRun;
   private final boolean isSuperuser;
-  private final TransportCredentials credentials;
   private final byte[] inputXmlBytes;
   private final EppMetrics metrics;
   private final Clock clock;
 
+
   public FlowRunner(
       Class<? extends Flow> flowClass,
       EppInput eppInput,
       Trid trid,
       SessionMetadata sessionMetadata,
       TransportCredentials credentials,
+      EppRequestSource eppRequestSource,
       boolean isDryRun,
       boolean isSuperuser,
       byte[] inputXmlBytes,
       final EppMetrics metrics,
       Clock clock) {
-    credentials.toString();
     this.flowClass = flowClass;
     this.eppInput = eppInput;
     this.trid = trid;
     this.sessionMetadata = sessionMetadata;
     this.credentials = credentials;
+    this.eppRequestSource = eppRequestSource;
     this.isDryRun = isDryRun;
     this.isSuperuser = isSuperuser;
     this.inputXmlBytes = inputXmlBytes;
@@ -84,6 +87,7 @@ public class FlowRunner {
         sessionMetadata,
         prettyPrint(inputXmlBytes).replaceAll("\n", "\n\t"),
         credentials,
+        eppRequestSource,
         isDryRun ? "DRY_RUN" : "LIVE",
         isSuperuser ? "SUPERUSER" : "NORMAL");
     if (!isTransactional()) {
@@ -138,6 +142,7 @@ public class FlowRunner {
           trid,
           sessionMetadata,
           credentials,
+          eppRequestSource,
           isSuperuser,
           now,
           inputXmlBytes);