JSON Serialization

/**
 * Jackson module for customizing Swagger 2 JSON serialization
 * Extends SimpleModule and implements JacksonModuleRegistrar for Spring integration
 */
public class Swagger2JacksonModule extends SimpleModule implements JacksonModuleRegistrar {
    
    /**
     * Conditionally registers this module with the provided ObjectMapper
     * Only registers if no existing Swagger mix-in is already configured
     * Also disables FAIL_ON_EMPTY_BEANS serialization failure
     * 
     * @param objectMapper The Jackson ObjectMapper to register with
     */
    public void maybeRegisterModule(ObjectMapper objectMapper);
    
    /**
     * Sets up Jackson serialization mix-ins for Swagger 2 types
     * Configures custom serialization behavior for all Swagger model objects
     * 
     * @param context Jackson module setup context
     */
    public void setupModule(SetupContext context);
}

// Typically configured automatically by Spring Boot
ObjectMapper objectMapper = new ObjectMapper();
Swagger2JacksonModule module = new Swagger2JacksonModule();
module.maybeRegisterModule(objectMapper);

// Manual registration
objectMapper.registerModule(new Swagger2JacksonModule());

/**
 * Mix-in class that configures common serialization settings for Swagger types
 * Applied to: Swagger, Info, License, Scheme, SecurityRequirement, SecuritySchemeDefinition,
 * Model, Operation, Path, Parameter, ExternalDocs, Xml, Tag, Contact
 */
@JsonAutoDetect
@JsonInclude(value = JsonInclude.Include.NON_EMPTY)
private class CustomizedSwaggerSerializer {
}

/**
 * Mix-in class specifically for Response objects
 * Ignores the 'responseSchema' property during serialization
 */
@JsonAutoDetect
@JsonInclude(value = JsonInclude.Include.NON_EMPTY)
@JsonIgnoreProperties("responseSchema")
private class ResponseSerializer {
}

/**
 * Mix-in interface for Property example serialization
 * Applies custom serialization logic to example values
 */
@JsonAutoDetect
@JsonInclude(value = JsonInclude.Include.NON_EMPTY)
private interface PropertyExampleSerializerMixin {
    
    /**
     * Custom serialization for example values
     * Handles string literals, JSON objects, arrays, and primitive values
     */
    @JsonSerialize(using = PropertyExampleSerializer.class)
    Object getExample();
}

/**
 * Custom Jackson serializer for property example values
 * Handles various data types and JSON formatting requirements
 */
public static class PropertyExampleSerializer extends StdSerializer<Object> {
    
    /**
     * Serializes example values with proper JSON formatting
     * Handles string literals, JSON objects, arrays, and primitive types
     * 
     * @param value The example value to serialize
     * @param gen Jackson JSON generator
     * @param provider Serializer provider
     */
    public void serialize(Object value, JsonGenerator gen, SerializerProvider provider) throws IOException;
    
    /**
     * Determines if a value should be considered empty
     * @param value The value to check
     * @return true if the value is null or empty string
     */
    public boolean isEmpty(Object value);
}

// String literals (quoted strings)
"example": "hello world"

// JSON objects 
"example": {"key": "value", "number": 42}

// JSON arrays
"example": [1, 2, 3, "item"]

// Boolean values
"example": true

// Numeric values  
"example": 42.5

// Raw JSON (when input is already valid JSON)
"example": {"raw": "json"}

/**
 * Checks if a string value is a quoted literal
 * @param value String to check
 * @return true if starts and ends with quotes (single or double)
 */
boolean isStringLiteral(String value);

/**
 * Checks if a string represents valid JSON (not a plain string)
 * Detects objects, arrays, booleans, and numbers
 * @param value String to check
 * @return true if the string is valid JSON
 */
boolean isNotJsonString(String value);

@Configuration
@EnableSwagger2WebMvc
public class SwaggerConfig {
    // Swagger2JacksonModule is automatically configured
}

@Configuration
public class JacksonConfig {
    
    @Bean
    @Primary
    public ObjectMapper objectMapper() {
        ObjectMapper mapper = new ObjectMapper();
        
        // Register Swagger 2 module
        Swagger2JacksonModule swagger2Module = new Swagger2JacksonModule();
        swagger2Module.maybeRegisterModule(mapper);
        
        return mapper;
    }
}