CORDA-2345: Updated docs to use the new TestCordapp API, rather than the old scan cordapp packages (#4491)

Also made some improvements to the API, especially for Java users.

docs/source/example-code/src/main/java/net/corda/docs/java/MockNetworkTestsTutorial.java

@@ -0,0 +1,35 @@
+package net.corda.docs.java;
+
+// DOCSTART 1
+import net.corda.core.identity.CordaX500Name;
+import net.corda.testing.node.MockNetwork;
+import net.corda.testing.node.MockNetworkParameters;
+import net.corda.testing.node.StartedMockNode;
+import org.junit.After;
+import org.junit.Before;
+
+import static java.util.Collections.singletonList;
+import static net.corda.testing.node.TestCordapp.findCordapp;
+
+public class MockNetworkTestsTutorial {
+
+    private final MockNetwork mockNet = new MockNetwork(new MockNetworkParameters(singletonList(findCordapp("com.mycordapp.package"))));
+
+    @After
+    public void cleanUp() {
+        mockNet.stopNodes();
+    }
+// DOCEND 1
+
+// DOCSTART 2
+    private StartedMockNode nodeA;
+    private StartedMockNode nodeB;
+
+    @Before
+    public void setUp() {
+        nodeA = mockNet.createNode();
+        // We can optionally give the node a name.
+        nodeB = mockNet.createNode(new CordaX500Name("Bank B", "London", "GB"));
+    }
+// DOCEND 2
+}

docs/source/example-code/src/main/kotlin/net/corda/docs/kotlin/MockNetworkTestsTutorial.kt

@@ -0,0 +1,33 @@
+package net.corda.docs.kotlin
+
+// DOCSTART 1
+import net.corda.core.identity.CordaX500Name
+import net.corda.testing.node.MockNetwork
+import net.corda.testing.node.MockNetworkParameters
+import net.corda.testing.node.StartedMockNode
+import net.corda.testing.node.TestCordapp.Companion.findCordapp
+import org.junit.After
+import org.junit.Before
+
+class MockNetworkTestsTutorial {
+
+    private val mockNet = MockNetwork(MockNetworkParameters(listOf(findCordapp("com.mycordapp.package"))))
+
+    @After
+    fun cleanUp() {
+        mockNet.stopNodes()
+    }
+// DOCEND 1
+
+// DOCSTART 2
+    private lateinit var nodeA: StartedMockNode
+    private lateinit var nodeB: StartedMockNode
+
+    @Before
+    fun setUp() {
+        nodeA = mockNet.createNode()
+        // We can optionally give the node a name.
+        nodeB = mockNet.createNode(CordaX500Name("Bank B", "London", "GB"))
+    }
+// DOCEND 2
+}