FIX: StackOverflowError when using recursive relation within Map

(cherry picked from commit d06bc13b4e1e421546f4997900d5fdc6aa980257)

ebean-api/src/main/java/io/ebean/bean/ToStringBuilder.java

@@ -1,7 +1,10 @@
 package io.ebean.bean;
 
+import io.ebean.common.BeanMap;
+
 import java.util.Collection;
 import java.util.IdentityHashMap;
+import java.util.Map;
 
 /**
  * Helps build toString content taking into account recursion.
@@ -104,6 +107,8 @@ public final class ToStringBuilder {
       }
     } else if (value instanceof Collection) {
       addCollection((Collection<?>) value);
+    } else if (value instanceof Map) {
+      addMap(((Map<?, ?>) value));
     } else {
       String content = String.valueOf(value);
       if (content.length() > TRIM_LENGTH) {
@@ -117,6 +122,28 @@ public final class ToStringBuilder {
     }
   }
 
+  public void addMap(Map<?,?> map) {
+    if (map == null || map.isEmpty()) {
+      sb.append("{}");
+    } else {
+      boolean firstElement = true;
+      sb.append("{");
+      for (Map.Entry<?, ?> entry : map.entrySet()) {
+        if (firstElement) {
+          firstElement = false;
+        } else {
+          sb.append(", ");
+        }
+        sb.append(entry.getKey()).append(":");
+        value(entry.getValue());
+        if (counter > MAX) {
+          return;
+        }
+      }
+      sb.append("}");
+    }
+  }
+
   /**
    * Add a collection of values.
    */

ebean-api/src/test/java/io/ebean/bean/ToStringBuilderTest.java

@@ -166,12 +166,76 @@ class ToStringBuilderTest {
     assertThat(toStringFor(list)).isEqualTo("{a:Recurse@1(id:1, nm:a), b:Recurse@2(id:2, nm:b)}");
   }
 
+  @Test
+  void map_recurse() {
+    final ParamStore paramStore = new ParamStore(1);
+
+    paramStore.map.put("aaa", new ParamValue(1, paramStore));
+    paramStore.map.put("bbb", new ParamValue(2, paramStore));
+
+    assertThat(toStringFor(paramStore))
+      .isEqualTo("ParamStore@0(id:1, map:{aaa:ParamValue@1(id:1, pm:ParamStore@0), bbb:ParamValue@2(id:2, pm:ParamStore@0)})");
+  }
+
   private String toStringFor(ToStringAware aware) {
     ToStringBuilder builder = new ToStringBuilder();
     aware.toString(builder);
     return builder.toString();
   }
 
+  static final class ParamValue implements ToStringAware {
+
+    final int id;
+
+    final ParamStore parentModel;
+
+    ParamValue(final int id, final ParamStore parentModel) {
+      this.id = id;
+      this.parentModel = parentModel;
+    }
+
+    public String toString() {
+      ToStringBuilder builder = new ToStringBuilder();
+      toString(builder);
+      return builder.toString();
+    }
+
+    @Override
+    public void toString(ToStringBuilder builder) {
+      builder.start(this);
+      builder.add("id", id);
+      builder.add("pm", parentModel);
+      builder.end();
+    }
+  }
+
+  static final class ParamStore implements ToStringAware {
+
+    final int id;
+
+    final Map<String, ParamValue> map = new HashMap<>();
+
+
+    ParamStore(final int id) {
+      this.id = id;
+    }
+
+    public String toString() {
+      ToStringBuilder builder = new ToStringBuilder();
+      toString(builder);
+      return builder.toString();
+    }
+
+    @Override
+    public void toString(ToStringBuilder builder) {
+      builder.start(this);
+      builder.add("id", id);
+      builder.add("map", map);
+      builder.end();
+    }
+  }
+
+
   static final class Recurse implements ToStringAware {
 
     final int id;