Add spring-ai recursive advisor demo using ToolCallAdvisor (#78)

Signed-off-by: Christian Tzolov <[email protected]>

Author: tzolov

advisors/recursive-advisor-demo/.gitattributes

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+/mvnw text eol=lf
+*.cmd text eol=crlf

advisors/recursive-advisor-demo/.gitignore

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+HELP.md
+target/
+.mvn/wrapper/maven-wrapper.jar
+!**/src/main/**/target/
+!**/src/test/**/target/
+
+### STS ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+build/
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### VS Code ###
+.vscode/

advisors/recursive-advisor-demo/.mvn/wrapper/maven-wrapper.properties

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+wrapperVersion=3.3.4
+distributionType=only-script
+distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.9.11/apache-maven-3.9.11-bin.zip

advisors/recursive-advisor-demo/README.md

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+# Spring AI Recursive Advisors Demo
+
+A Spring Boot demonstration project showcasing the new **Recursive Advisors** feature in Spring AI 1.1.0-M4+, which enables looping through advisor chains multiple times for iterative AI workflows.
+
+## Overview
+
+This project demonstrates the **Recursive Advisors** pattern using Spring AI's `ToolCallAdvisor` - a built-in recursive advisor that handles tool calling loops within the advisor chain. Key features shown:
+
+## Prerequisites
+
+- Java 17 or higher
+- Maven 3.6+
+- Anthropic API key
+
+## Key Components
+
+### 1. Main Application (`RecursiveAdvisorDemoApplication.java`)
+
+The main class demonstrates the recursive advisor pattern:
+
+```java
+ChatClient chatClient = chatClientBuilder
+    .defaultTools(new MyTools())
+    .defaultAdvisors(
+        ToolCallAdvisor.builder().build(),  // Built-in recursive advisor
+        new MyLogAdvisor())                 // Custom logging advisor
+    .build();
+```
+
+Key aspects:
+- **ToolCallAdvisor**: Built-in recursive advisor that loops until all tool calls are completed
+    - **User-Controlled Tool Execution**: Tools execute within the advisor chain, not inside the model
+- **Advisor Ordering**: Multiple advisors working together in the chain
+
+### 2. Custom Tools (`MyTools` class)
+
+```java
+@Tool(description = "Get the current weather for a given location")
+public String weather(String location) {
+    return "The current weather in " + location + " is sunny with a temperature of 25°C.";
+}
+```
+
+Demonstrates how to create custom tools that the AI can call during conversations.
+
+### 3. Custom Advisor (`MyLogAdvisor` class)
+
+Implements a non-recursive advisor to demonstrate observability in advisor chain flows:
+
+```java
+static class MyLogAdvisor implements BaseAdvisor {
+    @Override
+    public ChatClientRequest before(ChatClientRequest request, AdvisorChain chain) {
+        print("REQUEST", request.prompt().getInstructions());
+        return request;
+    }
+    
+    @Override
+    public ChatClientResponse after(ChatClientResponse response, AdvisorChain chain) {
+        print("RESPONSE", response.chatResponse().getResults());
+        return response;
+    }
+}
+```
+
+This advisor logs each iteration as the `ToolCallAdvisor` loops through tool executions, providing visibility into the recursive process.
+
+## Expected output 
+
+```
+REQUEST:[{"messageType":"USER","metadata":{"messageType":"USER"},"media":[],"text":"What is current weather in Paris?"}]
+
+RESPONSE:[{"metadata":{"finishReason":"tool_use","contentFilters":[],"empty":true},"output":{"messageType":"ASSISTANT","metadata":{"messageType":"ASSISTANT"},"toolCalls":[],"media":[],"text":"I'll check the current weather in Paris for you."}},{"metadata":{"finishReason":"tool_use","contentFilters":[],"empty":true},"output":{"messageType":"ASSISTANT","metadata":{"messageType":"ASSISTANT"},"toolCalls":[{"id":"toolu_01HNde1Z7mwtwXh4qiK3tavZ","type":"function","name":"weather","arguments":"{\"location\":\"Paris\"}"}],"media":[],"text":""}}]
+
+REQUEST:[{"messageType":"USER","metadata":{"messageType":"USER"},"media":[],"text":"What is current weather in Paris?"},{"messageType":"ASSISTANT","metadata":{"messageType":"ASSISTANT"},"toolCalls":[{"id":"toolu_01HNde1Z7mwtwXh4qiK3tavZ","type":"function","name":"weather","arguments":"{\"location\":\"Paris\"}"}],"media":[],"text":""},{"messageType":"TOOL","metadata":{"messageType":"TOOL"},"responses":[{"id":"toolu_01HNde1Z7mwtwXh4qiK3tavZ","name":"weather","responseData":"\"The current weather in Paris is sunny with a temperature of 25°C.\""}],"text":""}]
+
+RESPONSE:[{"metadata":{"finishReason":"end_turn","contentFilters":[],"empty":true},"output":{"messageType":"ASSISTANT","metadata":{"messageType":"ASSISTANT"},"toolCalls":[],"media":[],"text":"The current weather in Paris is sunny with a temperature of 25°C."}}]
+
+The current weather in Paris is sunny with a temperature of 25°C.
+```