title: I can not Inject Map<String, String> from yaml in spring boot
body: <p>I have this values in application.yaml</p>
  
  <pre><code>import-charge-fields:
    4: billDate
    1001: validUntil
    7: totalAmount
    24: purpose
  </code></pre>
  
  <p>And in service I try inject it:</p>
  
  <pre><code>    @Value("${import-charge-fields}")
      private Map&lt;String, String&gt; fields;
  </code></pre>
  
  <p>But I get exception:</p>
  
  <blockquote>
    <p>Caused by: java.lang.IllegalArgumentException: Could not resolve
    placeholder 'import-charge-fields' in value "${import-charge-fields}"</p>
  </blockquote>
  
  <p>I try this:</p>
  
  <pre><code>charge:
    hz: 123
    fields:
      4: billDate
      1001: validUntil
      7: totalAmount
      24: purpose
  </code></pre>
  
  <p>and </p>
  
  <pre><code>@Getter
  @Setter
  @Component
  @ConfigurationProperties(prefix = "charge")
  public class ChargeFields {
     private String hz;
     private Map&lt;String, String&gt; fields;
  }
  </code></pre>
  
  <p>and </p>
  
  <pre><code>@Value("${charge.hz}")
  private String hz;
  
  @Value("${charge.fields}")
  private Map&lt;String, String&gt; fields;
  </code></pre>
  
  <p>and it not work</p>