Lombok Singular

Singular.java

package lombok;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * This annotation can be used on a field of a builder class to let lombok generate an add method for adding a single
 * element to the collection behind the field.
 * <p>
 * This annotation is honored by {@code @Builder}.
 * 
 * @see Singulars
 */
@Target({ ElementType.FIELD, ElementType.METHOD })
@Retention(RetentionPolicy.SOURCE)
public @interface Singular {
	/**
	 * If the singular parameter name is not something that can be inferred from the variable name, specify it here.
	 * 
	 * @return Name of the singular method.
	 */
	String value() default "";
	
	/**
	 * If this and the {@code value} parameter are both absent, lombok will attempt to guess the name of the singular
	 * method by removing common collection prefixes (e.g. {@code set}, {@code map}) from the name of the variable that
	 * the annotation is put on.
	 * 
	 * @return Name of the variable the annotation is put on.
	 */
	String[] excludes() default {};
	
	/**
	 * If true, and the field is not initialized with an instance, lombok will generate a new instance for the field.
	 * 
	 * @return Whether to generate a new instance if none is found.
	 */
	boolean force() default false;
	
	/**
	 * If this value is not empty, the generated method will be annotated with this value.
	 * 
	 * @return The annotation to place on the generated method.
	 */
	String onMethod() default "";
	
	/**
	 * Set to true (default is false) to generate an 'addFooIfAbsent' method instead of an 'addFoo' method. This can
	 * improve readability of code that adds elements to a collection where it matters that the element isn't already in
	 * the collection.
	 * 
	 * @return Whether to generate an 'addFooIfAbsent' method.
	 */
	boolean addIfAbsent() default false;
	
	/**
	 * When using this annotation on a field of type {@code java.util.Map<K,V>}, you can use this attribute to specify the
	 * name of the parameter for the key of the map. This is useful if the name of the field does not contain enough
	 * information to infer the name of the key parameter.
	 * 
	 * @return Name of the key parameter.
	 */
	String key() default "";
	
	/**
	 * When using this annotation on a field of type {@code java.util.Map<K,V>}, you can use this attribute to specify the
	 * name of the parameter for both the key and value of the map. This is useful if the name of the field does not
	 * contain enough information to infer the names of the key and value parameters.
	 * 
	 * @return Name of the key and value parameters.
	 */
	String entry() default "";
	
	/**
	 * If present, lombok will add the given {@code @Deprecated} annotation to the generated method.
	 * 
	 * @return The {@code @Deprecated} annotation to add to the generated method.
	 */
	DeprecatedDeprecation deprecation() default @DeprecatedDeprecation;
	
	/**
	 * If present, lombok will make the generated method deprecated and adds the given message to the @Deprecated
	 * annotation.
	 * 
	 * @return The message for the @Deprecated annotation.
	 */
	String de