Access restriction: The type xxx is not API (restriction

Generally, we can see this in eclipse, as visit a non-public API is forbidden, such as sun.misc.Unsafe. Here I want to cancel this check temporarily.
steps as follow:

step1. find project properties, and click on ‘build path’

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step2. double click ‘Access rules’ or just edit it

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step3. add a ‘rule’, fill blanks like this. project rebuild.

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