core/src/com/google/inject/internal/util/Classes.java
public static Class<? extends Member> memberType(Member member) {
    checkNotNull(member, "member");

    if (member instanceof Field) {
      return Field.class;

    } else if (member instanceof Method) {
      return Method.class;

    } else if (member instanceof Constructor) {
      return Constructor.class;

    } else {
      throw new IllegalArgumentException(
          "Unsupported implementation class for Member, " + member.getClass());
    }
  }
public static Class<? extends Member> memberType(Member member) {
    checkNotNull(member, "member");

    if (member instanceof Field) {
      return Field.class;

    } else if (member instanceof Method) {
      return Method.class;

    } else if (member instanceof Constructor) {
      return Constructor.class;

    } else {
      throw new IllegalArgumentException(
          "Unsupported implementation class for Member, " + member.getClass());
    }
  }
Returns {@code Field.class}, {@code Method.class} or {@code Constructor.class}.