core: Remove com.google.common.collect usages, again

Commit 656e8ce (#2208) removed most usages, but missed one and one was
re-added. Since all usages are removed, it should be much easier to
notice regressions.

core/src/main/java/io/grpc/ResolvedServerInfoGroup.java

@@ -35,7 +35,6 @@ import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 
 import com.google.common.base.Objects;
-import com.google.common.collect.ImmutableList;
 
 import java.net.SocketAddress;
 import java.util.ArrayList;
@@ -64,7 +63,8 @@ public final class ResolvedServerInfoGroup {
   private ResolvedServerInfoGroup(List<ResolvedServerInfo> resolvedServerInfoList,
       Attributes attributes) {
     checkArgument(!resolvedServerInfoList.isEmpty(), "empty server list");
-    this.resolvedServerInfoList = Collections.unmodifiableList(resolvedServerInfoList);
+    this.resolvedServerInfoList =
+        Collections.unmodifiableList(new ArrayList<ResolvedServerInfo>(resolvedServerInfoList));
     this.attributes = checkNotNull(attributes, "attributes");
   }
 
@@ -148,11 +148,10 @@ public final class ResolvedServerInfoGroup {
   }
 
   public static class Builder {
-    private final ImmutableList.Builder<ResolvedServerInfo> groupBuilder;
+    private final List<ResolvedServerInfo> group = new ArrayList<ResolvedServerInfo>();
     private final Attributes attributes;
 
     public Builder(Attributes attributes) {
-      this.groupBuilder = ImmutableList.builder();
       this.attributes = attributes;
     }
 
@@ -161,17 +160,17 @@ public final class ResolvedServerInfoGroup {
     }
 
     public Builder add(ResolvedServerInfo resolvedServerInfo) {
-      groupBuilder.add(resolvedServerInfo);
+      group.add(resolvedServerInfo);
       return this;
     }
 
     public Builder addAll(Collection<ResolvedServerInfo> resolvedServerInfo) {
-      groupBuilder.addAll(resolvedServerInfo);
+      group.addAll(resolvedServerInfo);
       return this;
     }
 
     public ResolvedServerInfoGroup build() {
-      return new ResolvedServerInfoGroup(groupBuilder.build(), attributes);
+      return new ResolvedServerInfoGroup(group, attributes);
     }
   }
 }

core/src/main/java/io/grpc/internal/RoundRobinServerList.java

@@ -32,7 +32,6 @@
 package io.grpc.internal;
 
 import com.google.common.annotations.VisibleForTesting;
-import com.google.common.collect.Iterators;
 
 import io.grpc.EquivalentAddressGroup;
 import io.grpc.Status;
@@ -44,6 +43,7 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
+import java.util.NoSuchElementException;
 
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.NotThreadSafe;
@@ -62,7 +62,7 @@ public class RoundRobinServerList<T> {
   private RoundRobinServerList(TransportManager<T> tm, List<EquivalentAddressGroup> list) {
     this.tm = tm;
     this.list = list;
-    this.cyclingIter = Iterators.cycle(list);
+    this.cyclingIter = new CycleIterator<EquivalentAddressGroup>(list);
     this.requestDroppingTransport =
       tm.createFailingTransport(Status.UNAVAILABLE.withDescription("Throttled by LB"));
   }
@@ -136,4 +136,36 @@ public class RoundRobinServerList<T> {
           Collections.unmodifiableList(new ArrayList<EquivalentAddressGroup>(list)));
     }
   }
+
+  private static final class CycleIterator<T> implements Iterator<T> {
+    private final List<T> list;
+    private int index;
+
+    public CycleIterator(List<T> list) {
+      this.list = list;
+    }
+
+    @Override
+    public boolean hasNext() {
+      return !list.isEmpty();
+    }
+
+    @Override
+    public T next() {
+      if (!hasNext()) {
+        throw new NoSuchElementException();
+      }
+      T val = list.get(index);
+      index++;
+      if (index >= list.size()) {
+        index -= list.size();
+      }
+      return val;
+    }
+
+    @Override
+    public void remove() {
+      throw new UnsupportedOperationException();
+    }
+  }
 }