xds: Rename parseCluster() back to processCluster() for consistency

This is to keep names of the top-level process* functions called from
handle*Response functions, and returning *Update resources consistent:

- `handleLdsResponse()` -> `LdsUpdate processClientSideListener()`
                           `LdsUpdate processServerSideListener()`
- `handleCdsResponse()` -> `CdsUpdate processCluster()`
- `handleRdsResponse()` -> `RdsUpdate processRouteConfiguration()`
- `handleEdsResponse()` -> `EdsUpdate processClusterLoadAssignment()`

For some reason, processCluster() was renamed to parseCluster() in
fa4b980.

xds/src/main/java/io/grpc/xds/ClientXdsClient.java

@@ -1485,7 +1485,7 @@ public void handleCdsResponse(
         if (getBootstrapInfo() != null && getBootstrapInfo().certProviders() != null) {
           certProviderInstances = getBootstrapInfo().certProviders().keySet();
         }
-        cdsUpdate = parseCluster(cluster, retainedEdsResources, certProviderInstances, serverInfo);
+        cdsUpdate = processCluster(cluster, retainedEdsResources, certProviderInstances, serverInfo);
       } catch (ResourceInvalidException e) {
         errors.add(
             "CDS response Cluster '" + clusterName + "' validation error: " + e.getMessage());
@@ -1503,7 +1503,7 @@ public void handleCdsResponse(
   }
 
   @VisibleForTesting
-  static CdsUpdate parseCluster(Cluster cluster, Set<String> retainedEdsResources,
+  static CdsUpdate processCluster(Cluster cluster, Set<String> retainedEdsResources,
       Set<String> certProviderInstances, ServerInfo serverInfo)
       throws ResourceInvalidException {
     StructOrError<CdsUpdate.Builder> structOrError;

xds/src/test/java/io/grpc/xds/ClientXdsClientDataTest.java

@@ -1353,7 +1353,7 @@ public void parseCluster_ringHashLbPolicy_defaultLbConfig() throws ResourceInval
         .setLbPolicy(LbPolicy.RING_HASH)
         .build();
 
-    CdsUpdate update = ClientXdsClient.parseCluster(
+    CdsUpdate update = ClientXdsClient.processCluster(
         cluster, new HashSet<String>(), null, LRS_SERVER_INFO);
     assertThat(update.lbPolicy()).isEqualTo(CdsUpdate.LbPolicy.RING_HASH);
     assertThat(update.minRingSize())
@@ -1381,7 +1381,7 @@ public void parseCluster_transportSocketMatches_exception() throws ResourceInval
     thrown.expect(ResourceInvalidException.class);
     thrown.expectMessage(
         "Cluster cluster-foo.googleapis.com: transport-socket-matches not supported.");
-    ClientXdsClient.parseCluster(cluster, new HashSet<String>(), null, LRS_SERVER_INFO);
+    ClientXdsClient.processCluster(cluster, new HashSet<String>(), null, LRS_SERVER_INFO);
   }
 
   @Test
@@ -1406,7 +1406,7 @@ public void parseCluster_ringHashLbPolicy_invalidRingSizeConfig_minGreaterThanMa
 
     thrown.expect(ResourceInvalidException.class);
     thrown.expectMessage("Cluster cluster-foo.googleapis.com: invalid ring_hash_lb_config");
-    ClientXdsClient.parseCluster(cluster, new HashSet<String>(), null, LRS_SERVER_INFO);
+    ClientXdsClient.processCluster(cluster, new HashSet<String>(), null, LRS_SERVER_INFO);
   }
 
   @Test
@@ -1433,7 +1433,7 @@ public void parseCluster_ringHashLbPolicy_invalidRingSizeConfig_tooLargeRingSize
 
     thrown.expect(ResourceInvalidException.class);
     thrown.expectMessage("Cluster cluster-foo.googleapis.com: invalid ring_hash_lb_config");
-    ClientXdsClient.parseCluster(cluster, new HashSet<String>(), null, LRS_SERVER_INFO);
+    ClientXdsClient.processCluster(cluster, new HashSet<String>(), null, LRS_SERVER_INFO);
   }
 
   @Test