HBASE-23653 Expose content of meta table in web ui

Adds a display of the content of 'hbase:meta' to the Master's
table.jsp, when that table is selected. Supports basic pagination,
filtering, &c.

Author: ndimiduk

hbase-client/src/main/java/org/apache/hadoop/hbase/RegionLocations.java

@@ -18,7 +18,10 @@
 
 package org.apache.hadoop.hbase;
 
+import java.util.Arrays;
 import java.util.Collection;
+import java.util.Iterator;
+
 import org.apache.hadoop.hbase.client.RegionInfo;
 import org.apache.hadoop.hbase.client.RegionReplicaUtil;
 import org.apache.hadoop.hbase.util.Bytes;
@@ -31,7 +34,7 @@
  * (assuming small number of locations)
  */
 @InterfaceAudience.Private
-public class RegionLocations {
+public class RegionLocations implements Iterable<HRegionLocation> {
 
   private final int numNonNullElements;
 
@@ -361,6 +364,11 @@ public HRegionLocation getRegionLocation() {
     return null;
   }
 
+  @Override
+  public Iterator<HRegionLocation> iterator() {
+    return Arrays.asList(locations).iterator();
+  }
+
   @Override
   public String toString() {
     StringBuilder builder = new StringBuilder("[");

hbase-client/src/main/java/org/apache/hadoop/hbase/client/TableDescriptorBuilder.java

@@ -49,6 +49,7 @@
 import org.apache.hadoop.hbase.shaded.protobuf.generated.HBaseProtos;
 
 /**
+ * Convenience class for composing an instance of {@link TableDescriptor}.
  * @since 2.0.0
  */
 @InterfaceAudience.Public

hbase-server/pom.xml

@@ -436,6 +436,11 @@
       <artifactId>hamcrest-core</artifactId>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>org.hamcrest</groupId>
+      <artifactId>hamcrest-library</artifactId>
+      <scope>test</scope>
+    </dependency>
     <dependency>
       <groupId>org.bouncycastle</groupId>
       <artifactId>bcprov-jdk15on</artifactId>