Update DOI RegEx pattern to be more restrictive.

Author: sowerstl

src/main/java/gov/osti/services/Validation.java

@@ -110,7 +110,7 @@ public class Validation {
     // regular expressions for validating email addresses and URLs
     protected static final Pattern EMAIL_PATTERN = Pattern.compile("^[_A-Za-z0-9-\\+]+(\\.[_A-Za-z0-9-]+)*@[A-Za-z0-9-]+(\\.[A-Za-z0-9]+)*(\\.[A-Za-z]{2,})$");
     protected static final Pattern URL_PATTERN = Pattern.compile("\\bhttps?://[-a-zA-Z0-9+&@#/%?=~_|!:,.;]*[-a-zA-Z0-9+&@#/%=~_|]");
-    protected static final Pattern DOI_PATTERN = Pattern.compile("10.\\d{4,9}/[-._;()/:A-Za-z0-9]+$");
+    protected static final Pattern DOI_PATTERN = Pattern.compile("^(?i)(?:doi:|https?:\\/\\/(?:dx[.])?doi[.]org\\/)?10.\\d{4,9}\\/[-._;()\\/:A-Za-z0-9]+$");
     protected static final Pattern ORCID_PATTERN = Pattern.compile("(?i)^\\s*(?:(?:https?:\\/\\/)?orcid\\.org\\/)?(\\d{4}(?:-?\\d{4}){2}(?:-?\\d{3}[\\dX]))\\s*$");
 
     @JsonIgnoreProperties (ignoreUnknown = true)