fixed map type issue

Author: HugoMario

src/main/java/io/swagger/codegen/v3/generators/java/SpringCodegen.java

@@ -22,16 +22,22 @@
 import io.swagger.v3.oas.models.Operation;
 import io.swagger.v3.oas.models.PathItem;
 import io.swagger.v3.oas.models.media.ArraySchema;
+import io.swagger.v3.oas.models.media.MapSchema;
 import io.swagger.v3.oas.models.media.Schema;
-import org.apache.commons.lang3.StringUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.io.File;
 import java.io.IOException;
 import java.io.Writer;
 import java.net.URL;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.LinkedHashMap;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
 import java.util.regex.Matcher;
 import java.util.stream.Collectors;
 
@@ -475,7 +481,7 @@ public CodegenProperty fromProperty(String name, Schema propertySchema) {
         CodegenProperty codegenProperty = super.fromProperty(name, propertySchema);
         if (propertySchema != null && propertySchema.get$ref() != null) {
             Schema refSchema = OpenAPIUtil.getSchemaFromRefSchema(propertySchema, this.openAPI);
-            if (refSchema != null  && !isObjectSchema(refSchema) && !(refSchema instanceof ArraySchema) && refSchema.getEnum() == null) {
+            if (refSchema != null  && !isObjectSchema(refSchema) && !(refSchema instanceof ArraySchema) && !(refSchema instanceof MapSchema) && refSchema.getEnum() == null) {
                 setSchemaProperties(name, codegenProperty, refSchema);
                 processPropertySchemaTypes(name, codegenProperty, refSchema);
             }