switching to Collections from Guava for empty iterator

Author: Matt Darwin

java/vector/src/main/java/org/apache/arrow/vector/BaseValueVector.java

@@ -17,6 +17,7 @@
  */
 package org.apache.arrow.vector;
 
+import java.util.Collections;
 import java.util.Iterator;
 
 import com.google.flatbuffers.FlatBufferBuilder;
@@ -98,9 +99,7 @@ public void reset() {}
  }
 
  @Override
- public Iterator<ValueVector> iterator() {
- return Iterators.emptyIterator();
- }
+ public Iterator<ValueVector> iterator() { return Collections.emptyIterator(); }
 
  public static boolean checkBufRefs(final ValueVector vv) {
  for(final ArrowBuf buffer : vv.getBuffers(false)) {