Add upstream headers, remove redundant copies of Guava classes

Author: polyfractal

src/main/java/org/elasticsearch/search/aggregations/metrics/percentile/providers/qdigest/IQuantileEstimator.java

@@ -1,5 +1,10 @@
 package org.elasticsearch.search.aggregations.metrics.percentile.providers.qdigest;
 
+/**
+ * Upstream: Stream-lib, master @ 704002a2d8fa01fa7e9868dae9d0c8bedd8e9427
+ * https://github.com/addthis/stream-lib/blob/master/src/main/java/com/clearspring/analytics/stream/quantile/IQuantileEstimator.java
+ */
+
 public interface IQuantileEstimator
 {
     void offer(long value);

src/main/java/org/elasticsearch/search/aggregations/metrics/percentile/providers/qdigest/QDigest.java

@@ -16,6 +16,12 @@
 import java.util.Comparator;
 import java.util.List;
 
+/**
+ * Upstream: Stream-lib, master @ 704002a2d8fa01fa7e9868dae9d0c8bedd8e9427
+ * https://github.com/addthis/stream-lib/blob/master/src/main/java/com/clearspring/analytics/stream/quantile/QDigest.java
+ */
+
+
 /**
  * Q-Digest datastructure.
  * <p/>

src/main/java/org/elasticsearch/search/aggregations/metrics/percentile/providers/tdigest/AbstractIterator.java

@@ -21,6 +21,13 @@
 import java.util.ArrayDeque;
 import java.util.Deque;
 import java.util.Iterator;
+import com.google.common.collect.AbstractIterator;
+import com.google.common.base.Preconditions;
+
+/**
+ * Upstream: Stream-lib, master @ 704002a2d8fa01fa7e9868dae9d0c8bedd8e9427
+ * https://github.com/addthis/stream-lib/blob/master/src/main/java/com/clearspring/analytics/stream/quantile/GroupTree.java
+ */
 
 /**
  * A tree containing TDigest.Group.  This adds to the normal NavigableSet the

src/main/java/org/elasticsearch/search/aggregations/metrics/percentile/providers/tdigest/GroupTree.java

@@ -17,13 +17,20 @@
  * limitations under the License.
  */
 
+/**
+ * Upstream: Stream-lib, master @ 704002a2d8fa01fa7e9868dae9d0c8bedd8e9427
+ * https://github.com/addthis/stream-lib/blob/master/src/main/java/com/clearspring/analytics/stream/quantile/TDigest.java
+ */
 
 import java.nio.ByteBuffer;
 import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Random;
 import java.util.concurrent.atomic.AtomicInteger;
+import com.google.common.base.Preconditions;
+import com.google.common.collect.Lists;
+
 
 /**
  * Adaptive histogram based on something like streaming k-means crossed with Q-digest.