private ICompletionProposal[] makeCommandProposals(SQLCompletionRequest request, String prefix) {
        final String controlCommandPrefix = editor.getSyntaxManager().getControlCommandPrefix();
        if (prefix.startsWith(controlCommandPrefix)) {
            prefix = prefix.substring(controlCommandPrefix.length());
        }
        final List<SQLCommandCompletionProposal> commandProposals = new ArrayList<>();
        for (SQLCommandHandlerDescriptor command : SQLCommandsRegistry.getInstance().getCommandHandlers()) {
            if (command.getId().startsWith(prefix)) {
                commandProposals.add(new SQLCommandCompletionProposal(request, command));
            }
        }
        return commandProposals.toArray(new ICompletionProposal[0]);
    }
The SQL content assist processor. This content assist processor proposes text
completions and computes context information for a SQL content type.
plugins/org.jkiss.dbeaver.ui.editors.sql/src/org/jkiss/dbeaver/ui/editors/sql/syntax/SQLCompletionProcessor.java