feat: added yaml configuration support

.gitignore

@@ -16,3 +16,4 @@ deltaspike/core/impl/data
 deltaspike/modules/jsf/impl/data
 deltaspike/modules/security/impl/data
 *.log
+bin/

deltaspike/core/api/src/main/java/org/apache/deltaspike/core/util/MapUtils.java

@@ -0,0 +1,193 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.deltaspike.core.util;
+
+import jakarta.enterprise.inject.Typed;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.StringJoiner;
+
+/**
+ * Utility to flatten nested {@link Map}s into a single level key:value pair set
+ * of properties.
+ *
+ * @since 2.0.0
+ */
+@Typed
+public abstract class MapUtils
+{
+    /**
+     * Don't construct this class. Only use the <code>static</code> methods.
+     */
+    private MapUtils()
+    {
+        // Do nothing
+    }
+
+    /**
+     * Calls {@link #flattenMapProperties(Map, boolean)} with
+     * <code>indexed=false</code>.
+     *
+     * @param input Map of properties that may contain nested Maps.
+     * @param <V> Type of values the {@link Map} contains.
+     * @return Map of all properties indexed by their fully qualified names.
+     * @see #flattenMapProperties(Map, boolean)
+     */
+    public static <V> Map<String, String> flattenMapProperties(final Map<String, V> input)
+    {
+        return flattenMapProperties(input, false);
+    }
+
+    /**
+     * <p>Converts a {@link Map} of objects to a flattened {@link Map} of
+     * {@link String} values.</p>
+     *
+     * For example, with the given input:
+     *
+     * <pre><code>
+     * Map&lt;String, Object&gt; application = Map.of(
+     *     "name", "My App",
+     *     "prefixes", List.of("&gt;", "$")
+     * );
+     *
+     * Map&lt;String, Object&gt; map = Map.of("application", application);
+     * Map&lt;String, String&gt; result = MapUtils.flattenMapProperties(map);</code></pre>
+     *
+     * Will result in the following properties, assuming <code>indexed</code>
+     * is <code>false</code>:
+     *
+     * <pre><code>
+     * application.name=My App
+     * application.prefixes=&gt;,$</code></pre>
+     *
+     * If <code>indexed</code> is <code>true</code>, the result would be:
+     *
+     * <pre><code>
+     * application.name=My App
+     * application.prefixes[0]=&gt;
+     * application.prefixes[1]=$</code></pre>
+     *
+     *
+     * @param input Map of properties that may contain nested Maps.
+     * @param indexed If arrays are converted to multiple properties, or a comma separated list.
+     * @param <V> Type of values the {@link Map} contains.
+     * @return Map of all properties indexed by their fully qualified names.
+     */
+    public static <V> Map<String, String> flattenMapProperties(final Map<String, V> input, final boolean indexed)
+    {
+        final Map<String, String> result = new HashMap<>();
+        flattenMapProperties(input, result, indexed);
+        return result;
+    }
+
+    /**
+     * Calls {@link #flattenMapProperties(Map, Map, boolean, String)} with
+     * parameter <code>prefix</code> as <code>null</code>, since when we begin
+     * flattening the map, there is no prefix by default.
+     *
+     * @param input Map of properties that may contain nested Maps.
+     * @param output Map that all properties are added to.
+     * @param indexed If arrays are converted to multiple properties, or a comma separated list.
+     * @param <V> Type of values the {@link Map} contains.
+     * @see #flattenMapProperties(Map, Map, boolean, String)
+     */
+    private static <V> void flattenMapProperties(final Map<String, V> input,
+                                                 final Map<String, String> output,
+                                                 final boolean indexed)
+    {
+        flattenMapProperties(input, output, indexed, null);
+    }
+
+    /**
+     * @param input Map of properties that may contain nested Maps.
+     * @param output Map that all properties are added to.
+     * @param indexed If arrays are converted to multiple properties, or a comma separated list.
+     * @param prefix Name to prefix to any properties found on this level.
+     * @param <V> Type of values the {@link Map} contains.
+     */
+    private static <V> void flattenMapProperties(final Map<String, V> input,
+                                                 final Map<String, String> output,
+                                                 final boolean indexed,
+                                                 final String prefix)
+    {
+        input.forEach((key, value) ->
+            {
+                if (value == null)
+                {
+                    return;
+                }
+
+                final String k = (prefix == null) ? key : (prefix + '.' + key);
+
+                if (value instanceof Map)
+                {
+                    flattenMapProperties((Map) value, output, indexed, k);
+                }
+                else if (value instanceof Iterable)
+                {
+                    addIterable((Iterable) value, k, output, indexed);
+                }
+                else
+                {
+                    output.put(k, (output.containsKey(k)) ? output.get(k) + "," + value : value.toString());
+                }
+            });
+    }
+
+    /**
+     * @param value Array of values that needs to be flattened.
+     * @param key Property name for this value.
+     * @param output Map that all properties are added to.
+     * @param indexed If arrays are converted to multiple properties, or a comma separated list.
+     * @param <V> Type of values the {@link Map} contains.
+     */
+    private static <V> void addIterable(final Iterable<V> value,
+                                        final String key,
+                                        final Map<String, String> output,
+                                        final boolean indexed)
+    {
+        final StringJoiner joiner = new StringJoiner(",");
+        int index = 0;
+
+        for (final Object o : value)
+        {
+            if (o instanceof Map)
+            {
+                final Map map = (Map) o;
+
+                if (map.isEmpty())
+                {
+                    continue;
+                }
+
+                final String keyPrefix = (indexed) ? key + "[" + index++ + "]" : key;
+                flattenMapProperties((Map) map, output, indexed, keyPrefix);
+            }
+            else
+            {
+                joiner.add(o.toString());
+            }
+        }
+
+        if (joiner.length() > 0)
+        {
+            output.put(key, joiner.toString());
+        }
+    }
+}