Java EE IDE in webcontent folder always appears red cross

Multiple annotations found at this line:
- Access restriction: The method getParameter (String) from the type ServletRequest
is not accessible due to restriction on required library E: \ jdk \ jre \ lib \ ext \ servlet-api.jar
- Access restriction: The method getParameter (String) from the type ServletRequest
is not accessible due to restriction on required library E: \ jdk \ jre \ lib \ ext \ servlet-api.jar
- Element (CENTER) is obsolete Its use is discouraged in HTML5 documents..
I checked a lot , eh did not use the Internet , the god please help
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deleted rewritten, or reopen
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thank you, the problem has been resolved < br> ------ For reference only ---------------------------------------
landlord what the problem is it , eclipse problem or referenced lib library with no good ? Share with answers.