package org.kuali.common.httplib.inject;
   
   import static com.fasterxml.jackson.databind.SerializationFeature.FAIL_ON_EMPTY_BEANS;
   
   import javax.inject.Inject;
   import javax.inject.Provider;
   
   import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
   import com.fasterxml.jackson.databind.ObjectMapper;
  
  public final class ObjectMapperProvider implements Provider<ObjectMapper> {
  
      @Inject
      public ObjectMapperProvider(ObjectMapper mapper) {
          this.mapper = mapper.copy();
      }
  
      private final ObjectMapper mapper;
  
      @Override
      public ObjectMapper get() {
          mapper.configure(FAIL_ON_EMPTY_BEANS, false); // Some exceptions contain beans with no properties
          mapper.addMixIn(Throwable.class, ThrowableMixin.class);
          return mapper.copy();
      }
  
      // Doing this so Jackson doesn't fail on exceptions that aren't json friendly
      // Jackson ships with the ability to serialize/deserialize all the "normal" elements of any exception
      // The message and stacktrace always get handled perfectly.
      // However, some exceptions are odd ducks.
      // For example: java.io.InterruptedIOException declares a public int called "bytesTransferred" with no getter/setter methods.
      // Thus we ignore unknown properties so as to prevent ourselves from blowing up when converting from json -> object.
      // Ignoring unknown properties is lossy, ie "extra" properties of an exception get lost when cycling from object -> json -> object.
      // However, we won't blow up on funky exceptions containing properties that jackson doesn't know how to handle,
      // and the stacktrace and message both stay intact
      // It would be better to take advantage of Jackson's ability to preserve the specific type of
      // exception using mapper.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);
      // but there is some kind of issue with that and Guava's Optional class.
      // serializing/deserializing Optional<IOException> doesn't work correctly
      @JsonIgnoreProperties(ignoreUnknown = true)
      private static interface ThrowableMixin {}
  
  }