drools-eclipse/org.drools.eclipse/src/main/java/org/drools/eclipse/editors/completion/AbstractCompletionProcessor.java
protected static void filterProposalsOnPrefix(String prefix, List<ICompletionProposal> props) {
        if ( prefix != null && prefix.trim().length() > 0 ) {
            Iterator<ICompletionProposal> iterator = props.iterator();
            String prefixLc = prefix.toLowerCase();
            while ( iterator.hasNext() ) {
                ICompletionProposal item = iterator.next();
                String content = item.getDisplayString().toLowerCase();
                if ( !content.toLowerCase().startsWith( prefixLc ) ) {
                    iterator.remove();
                }
            }
        }
    }
protected static void filterProposalsOnPrefix(String prefix, List<ICompletionProposal> props) {
        if ( prefix != null && prefix.trim().length() > 0 ) {
            Iterator<ICompletionProposal> iterator = props.iterator();
            String prefixLc = prefix.toLowerCase();
            while ( iterator.hasNext() ) {
                ICompletionProposal item = iterator.next();
                String content = item.getDisplayString().toLowerCase();
                if ( !content.toLowerCase().startsWith( prefixLc ) ) {
                    iterator.remove();
                }
            }
        }
    }
Filter out the proposals whose content does not start with the given prefix.