public Type getFieldType() {
    return Type.intern(descriptor.getString());
  }
Gets the field type corresponding to this instance's descriptor. This method is only valid to
call if the descriptor in fact describes a field (and not a method).

@return {@code non-null;} the field type
android/android_framework/dex-maker/src/main/java/com/android/dx/rop/cst/CstNat.java