if ( this.modifiedDate != null )
issues.addAllIssues( this.modifiedDate.getIssues() );
if ( this.issuedDate != null )
issues.addAllIssues( this.issuedDate.getIssues() );
if ( this.validDate != null )
issues.addAllIssues( this.validDate.getIssues() );
if ( this.availableDate != null )
issues.addAllIssues( this.availableDate.getIssues() );
if ( this.metadataCreatedDate != null )
issues.addAllIssues( this.metadataCreatedDate.getIssues() );
if ( this.metadataModifiedDate != null )