OZG-7669 transfer fileid as string (not object)

src/main/java/de/ozgcloud/processor/vorgang/FileMetaData.java

@@ -23,6 +23,8 @@
  */
 package de.ozgcloud.processor.vorgang;
 
+import com.fasterxml.jackson.annotation.JsonProperty;
+
 import de.ozgcloud.common.binaryfile.FileId;
 import lombok.Builder;
 import lombok.Getter;
@@ -36,4 +38,9 @@ public class FileMetaData {
 	private String name;
 	private String contentType;
 	private long size;
+
+	@JsonProperty("id")
+	String getId() {
+		return id.toString();
+	}
 }