feat: implement entity endpoints

src/main/java/org/arkecosystem/client/api/Api.java

@@ -4,21 +4,23 @@
 
 public class Api {
 
-    public Blockchain blockchain;
-    public Blocks blocks;
-    public Delegates delegates;
-    public Locks locks;
-    public Node node;
-    public Peers peers;
-    public Rounds rounds;
-    public Transactions transactions;
-    public Votes votes;
-    public Wallets wallets;
+    public final Blockchain blockchain;
+    public final Blocks blocks;
+    public final Delegates delegates;
+    public final Entities entities;
+    public final Locks locks;
+    public final Node node;
+    public final Peers peers;
+    public final Rounds rounds;
+    public final Transactions transactions;
+    public final Votes votes;
+    public final Wallets wallets;
 
     public Api(Client client) {
         this.blockchain = new Blockchain(client);
         this.blocks = new Blocks(client);
         this.delegates = new Delegates(client);
+        this.entities = new Entities(client);
         this.locks = new Locks(client);
         this.node = new Node(client);
         this.peers = new Peers(client);

src/main/java/org/arkecosystem/client/api/Entities.java

@@ -0,0 +1,23 @@
+package org.arkecosystem.client.api;
+
+import org.arkecosystem.client.http.Client;
+
+import java.io.IOException;
+import java.util.Map;
+
+public class Entities {
+    private final Client client;
+
+    public Entities(Client client) {
+        this.client = client;
+    }
+
+    public Map<String, Object> all() throws IOException {
+        return this.client.get("entities");
+    }
+
+    public Map<String, Object> show(String id) throws IOException {
+        return this.client.get("entities/" + id);
+    }
+
+}

src/test/java/org/arkecosystem/client/api/EntitiesTest.java

@@ -0,0 +1,27 @@
+package org.arkecosystem.client.api;
+
+import org.arkecosystem.client.Connection;
+import org.arkecosystem.client.MockHelper;
+import org.junit.jupiter.api.Test;
+
+import java.io.IOException;
+import java.util.Map;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class EntitiesTest {
+
+    @Test
+    void all() throws IOException {
+        Connection connection = MockHelper.connection();
+        Map<String, Object> actual = connection.api().entities.all();
+        assertTrue((boolean) actual.get("success"));
+    }
+
+    @Test
+    void show() throws IOException {
+        Connection connection = MockHelper.connection();
+        Map<String, Object> actual = connection.api().entities.show("dummy");
+        assertTrue((boolean) actual.get("success"));
+    }
+}