Refactor MappingElasticsearchConverter.

* Add support for SpEL expressions via @value.
* Simplify readCollectionOrArray to consider properly nested lists and maps
* Simplify readMap to allow reading generic maps and entities in maps.
* Report a fallback TypeInformation in DefaultElasticsearchTypeMapper to properly convert nested maps.

We now no longer rely on isSimpleType when writing Maps. This is the preparation to consider Map as simple type.

Resolves #1676.
See #1675.

Author: mp911de

src/main/java/org/springframework/data/elasticsearch/core/convert/DefaultElasticsearchTypeMapper.java

@@ -26,6 +26,8 @@
 import org.springframework.data.mapping.Alias;
 import org.springframework.data.mapping.PersistentEntity;
 import org.springframework.data.mapping.context.MappingContext;
+import org.springframework.data.util.ClassTypeInformation;
+import org.springframework.data.util.TypeInformation;
 import org.springframework.lang.Nullable;
 
 /**
@@ -38,6 +40,9 @@
 public class DefaultElasticsearchTypeMapper extends DefaultTypeMapper<Map<String, Object>>
 		implements ElasticsearchTypeMapper {
 
+	@SuppressWarnings("rawtypes") //
+	private static final TypeInformation<Map> MAP_TYPE_INFO = ClassTypeInformation.from(Map.class);
+
 	private final @Nullable String typeKey;
 
 	public DefaultElasticsearchTypeMapper(@Nullable String typeKey) {
@@ -62,11 +67,23 @@ public DefaultElasticsearchTypeMapper(@Nullable String typeKey, TypeAliasAccesso
 		this.typeKey = typeKey;
 	}
 
-	@Override
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.core.convert.MongoTypeMapper#isTypeKey(java.lang.String)
+	 */
 	public boolean isTypeKey(String key) {
 		return typeKey != null && typeKey.equals(key);
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.convert.DefaultTypeMapper#getFallbackTypeFor(java.lang.Object)
+	 */
+	@Override
+	protected TypeInformation<?> getFallbackTypeFor(Map<String, Object> source) {
+		return MAP_TYPE_INFO;
+	}
+
 	/**
 	 * {@link TypeAliasAccessor} to store aliases in a {@link Map}.
 	 *