NIFI-15142 Added createBranch method to Flow Registry Client (#25)

Signed-off-by: David Handermann <[email protected]>

Author: pvillard31

src/main/java/org/apache/nifi/registry/flow/FlowRegistryClient.java

@@ -119,6 +119,27 @@ default FlowRegistryBranch getDefaultBranch(final FlowRegistryClientConfiguratio
         return branch;
     }
 
+    /**
+     * Creates a new branch in the Flow Registry for the specified flow.
+     *
+     * Implementations that do not support branching should rely on this default method, which throws an
+     * {@link UnsupportedOperationException}. Implementations that support branching must override this method
+     * and perform any required validation to ensure that the new branch can be created.
+     *
+     * @param context Configuration context
+     * @param sourceLocation The location of the flow version that will act as the source for the new branch. The version may be {@code null}
+     *                       to indicate that the registry implementation should select a default, such as the latest version on the source branch.
+     * @param branchName The name of the branch to create
+     *
+     * @throws FlowRegistryException If an issue happens during processing the request.
+     * @throws IOException If there is issue with the communication between NiFi and the Flow Registry.
+     * @throws UnsupportedOperationException If the registry does not support branching.
+     */
+    default void createBranch(FlowRegistryClientConfigurationContext context, FlowVersionLocation sourceLocation, String branchName)
+            throws FlowRegistryException, IOException {
+        throw new UnsupportedOperationException("Branch creation is not supported by this Flow Registry Client");
+    }
+
     /**
      * Gets the buckets for the specified user.
      *