'+' in regex should be escaped (#346)

Author: hauner

openapi-processor-core/src/main/resources/mapping/v16/mapping.yaml.json

@@ -518,7 +518,7 @@
     "InterfaceMappingFormat": {
       "description": "target =+ fully qualified interface type.",
       "type": "string",
-      "pattern": "^.+\\s+(=+|implement)\\s+.+$",
+      "pattern": "^.+\\s+(=\\+|implement)\\s+.+$",
       "examples": [
         "FooSchema =+ java.io.Serializable",
         "object =+ java.io.Serializable",