This commit partially reverts cf2429b0f0
in order to reinstate -Werror for Groovy compilation in spring-beans.
The `decorating` field in GroovyDynamicElementReader has been changed
from boolean to Boolean in order to avoid the JDK 17 deprecation warning
for use of `new Boolean(false)` which the Groovy compiler apparently
uses behind the scenes when compiling Groovy source code.