public synchronized void analyseUsage() {
if (! usageAnalyzed) {
ReferenceCounter rc = new ReferenceCounter();
compilationUnit.visit(rc);
compilationUnit.visit(new UsageVisitor(rc));
compilationUnit.visit(new DeprecationVisitor());
compilationUnit.visit(new WarningSuppressionVisitor<Warning>(Warning.class, suppressedWarnings));
usageAnalyzed = true;
}
}