core/src/com/google/inject/internal/Nullability.java

package com.google.inject.internal;

import java.lang.annotation.Annotation;

import com.google.inject.internal.util.Nullable;

/**
 * Whether a member supports null values injected.
 *
 * <p>Support for {@code Nullable} annotations in Guice is loose.
 * Any annotation type whose simplename is "Nullable" is sufficient to indicate
 * support for null values injected.
 *
 * <p>This allows support for JSR-305's
 * <a href="http://groups.google.com/group/jsr-305/web/proposed-annotations">
 * javax.annotation.meta.Nullable</a> annotation and IntelliJ IDEA's
 * <a href="http://www.jetbrains.com/idea/documentation/howto.html">
 * org.jetbrains.annotations.Nullable</a>.
 *
 * @author jessewilson@google.com (Jesse Wilson)
 */
public class Nullability {
  private Nullability() {}

  public static boolean allowsNull(Annotation[] annotations) {
    for(Annotation a : annotations) {
      Class<? extends Annotation> type = a.annotationType();
      // Check for Nullable.class because our c.g.i.internal.util.Nullable
      // gets jarjar'd into $Nullable, and we want extensions that reference
      // it to continue working.
      if ("Nullable".equals(type.getSimpleName()) || type == Nullable.class) {
        return true;
      }
    }
    return false;
  }
}