mistriggered "error: warnings found and -Werror specified" for java warnings

[Ralf H]

we don't need jtreg for this to occur:

Compiling 127 files for BUILD_java.compiler.interim
/home/ralf/build/openjdk-hg/src/java.compiler/share/classes/javax/lang/model/util/AbstractElementVisitor14.java:30:
warning: [preview] RecordComponentElement is an API that is part of a
preview feature
import javax.lang.model.element.RecordComponentElement;
                               ^
/home/ralf/build/openjdk-hg/src/java.compiler/share/classes/javax/lang/model/util/SimpleElementVisitor14.java:30:
warning: [preview] RecordComponentElement is an API that is part of a
preview feature
import javax.lang.model.element.RecordComponentElement;
                               ^
error: warnings found and -Werror specified

BOOT_JDK is made from openjdk-14 source of last november.

cheers,

-- Ralf