MINOR: Make some constructors in admin package public

Add a public create API that takes a Properties instance.

Make the constructors for TopicDescription, TopicListing
and TopicPartitionInfo public to enable AdminClient
users to write better tests.

Author: Colin P. Mccabe <cmccabe@confluent.io>

Reviewers: Ismael Juma <ismael@juma.me.uk>

Closes #3070 from cmccabe/publicapi

clients/src/main/java/org/apache/kafka/clients/admin/AdminClient.java

@@ -22,6 +22,7 @@ import org.apache.kafka.common.annotation.InterfaceStability;
 
 import java.util.Collection;
 import java.util.Map;
+import java.util.Properties;
 
 /**
  * The public interface for the {@link KafkaAdminClient}, which supports managing and inspecting topics,
@@ -31,6 +32,16 @@ import java.util.Map;
  */
 @InterfaceStability.Unstable
 public abstract class AdminClient implements AutoCloseable {
+    /**
+     * Create a new AdminClient with the given configuration.
+     *
+     * @param props         The configuration.
+     * @return              The new KafkaAdminClient.
+     */
+    public static AdminClient create(Properties props) {
+        return KafkaAdminClient.createInternal(new AdminClientConfig(props));
+    }
+
     /**
      * Create a new AdminClient with the given configuration.
      *
@@ -38,7 +49,7 @@ public abstract class AdminClient implements AutoCloseable {
      * @return              The new KafkaAdminClient.
      */
     public static AdminClient create(Map<String, Object> conf) {
-        return KafkaAdminClient.create(new AdminClientConfig(conf));
+        return KafkaAdminClient.createInternal(new AdminClientConfig(conf));
     }
 
     /**

clients/src/main/java/org/apache/kafka/clients/admin/KafkaAdminClient.java

@@ -238,7 +238,7 @@ public class KafkaAdminClient extends AdminClient {
         return throwable.getClass().getSimpleName();
     }
 
-    static KafkaAdminClient create(AdminClientConfig config) {
+    static KafkaAdminClient createInternal(AdminClientConfig config) {
         Metadata metadata = null;
         Metrics metrics = null;
         NetworkClient networkClient = null;

clients/src/main/java/org/apache/kafka/clients/admin/TopicDescription.java

@@ -29,7 +29,7 @@ public class TopicDescription {
     private final boolean internal;
     private final NavigableMap<Integer, TopicPartitionInfo> partitions;
 
-    TopicDescription(String name, boolean internal,
+    public TopicDescription(String name, boolean internal,
                     NavigableMap<Integer, TopicPartitionInfo> partitions) {
         this.name = name;
         this.internal = internal;

clients/src/main/java/org/apache/kafka/clients/admin/TopicListing.java

@@ -24,7 +24,7 @@ public class TopicListing {
     private final String name;
     private final boolean internal;
 
-    TopicListing(String name, boolean internal) {
+    public TopicListing(String name, boolean internal) {
         this.name = name;
         this.internal = internal;
     }

clients/src/main/java/org/apache/kafka/clients/admin/TopicPartitionInfo.java

@@ -28,7 +28,7 @@ public class TopicPartitionInfo {
     private final List<Node> replicas;
     private final List<Node> isr;
 
-    TopicPartitionInfo(int partition, Node leader, List<Node> replicas, List<Node> isr) {
+    public TopicPartitionInfo(int partition, Node leader, List<Node> replicas, List<Node> isr) {
         this.partition = partition;
         this.leader = leader;
         this.replicas = replicas;