#3 session API draft

stbf-common/src/main/java/ru/penkrat/stbf/common/session/InMemBotSessionProvider.java

@@ -0,0 +1,18 @@
+package ru.penkrat.stbf.common.session;
+
+import ru.penkrat.stbf.api.BotSession;
+import ru.penkrat.stbf.api.SessionProvider;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+public class InMemBotSessionProvider implements SessionProvider {
+
+    private static final Map<Long, BotSession> MAP = new ConcurrentHashMap<>();
+
+    @Override
+    public BotSession get(Long chatId) {
+        return MAP.computeIfAbsent(chatId, k -> new MapBackedBotSession(new ConcurrentHashMap<>()));
+    }
+
+}

stbf-common/src/main/java/ru/penkrat/stbf/common/session/MapBackedBotSession.java

@@ -0,0 +1,22 @@
+package ru.penkrat.stbf.common.session;
+
+import lombok.RequiredArgsConstructor;
+import ru.penkrat.stbf.api.BotSession;
+
+import java.util.Map;
+
+@RequiredArgsConstructor
+class MapBackedBotSession implements BotSession {
+
+    private final Map<String, Object> map;
+
+    @Override
+    public Object getAttribute(String name) {
+        return map.get(name);
+    }
+
+    @Override
+    public void setAttribute(String name, Object value) {
+        map.put(name, value);
+    }
+}