add support for prefix before header, allow comments in header json

src/main/java/org/cobbzilla/util/main/FileHeader.java

@@ -10,7 +10,10 @@ public class FileHeader {
     @Getter @Setter private String ext;
     @Getter @Setter private String header;
     @Getter @Setter private String regex;
-
     @Getter(lazy=true) private final Pattern pattern = Pattern.compile(getRegex()+"\n", Pattern.MULTILINE);
 
+    @Getter @Setter private String prefix;
+    public boolean hasPrefix () { return prefix != null; }
+    @Getter(lazy=true) private final Pattern prefixPattern = Pattern.compile(getPrefix()+"\n", Pattern.MULTILINE);
+
 }

src/main/java/org/cobbzilla/util/main/FileHeaderMain.java

@@ -24,12 +24,25 @@ public class FileHeaderMain extends BaseMain<FileHeaderOptions> {
                         if (header != null) {
                             String contents = toStringOrDie(file);
                             if (contents == null) contents = "";
+                            final String prefix;
+                            if (header.hasPrefix()) {
+                                final Matcher prefixMatcher = header.getPrefixPattern().matcher(contents);
+                                if (!prefixMatcher.find()) {
+                                    err("prefix not found ("+header.getPrefix().replace("\n", "\\n")+") in file: "+abs(file));
+                                    return;
+                                }
+                                prefix = contents.substring(0, prefixMatcher.start())
+                                        + contents.substring(prefixMatcher.start(), prefixMatcher.end());
+                                contents = contents.substring(prefixMatcher.end());
+                            } else {
+                                prefix = "";
+                            }
                             final Matcher matcher = header.getPattern().matcher(contents);
                             if (matcher.find()) {
-                                contents = contents.substring(0, matcher.start())
+                                contents = prefix + contents.substring(0, matcher.start())
                                         + header.getHeader() + "\n" + contents.substring(matcher.end());
                             } else {
-                                contents = header.getHeader() + "\n" + contents;
+                                contents = prefix + header.getHeader() + "\n" + contents;
                             }
                             out(abs(file));
                             toFileOrDie(file, contents);

src/main/java/org/cobbzilla/util/main/FileHeaderOptions.java

@@ -13,6 +13,7 @@ import java.util.Map;
 import java.util.stream.Collectors;
 
 import static java.util.function.Function.identity;
+import static org.cobbzilla.util.json.JsonUtil.FULL_MAPPER_ALLOW_COMMENTS;
 import static org.cobbzilla.util.json.JsonUtil.json;
 import static org.cobbzilla.util.string.StringUtil.UTF8cs;
 
@@ -37,7 +38,7 @@ public class FileHeaderOptions extends BaseMainOptions {
         } else {
             input = inStream(new File(headersJson));
         }
-        final FileHeader[] headers = json(IOUtils.toString(input, UTF8cs), FileHeader[].class);
+        final FileHeader[] headers = json(IOUtils.toString(input, UTF8cs), FileHeader[].class, FULL_MAPPER_ALLOW_COMMENTS);
         return Arrays.stream(headers).collect(Collectors.toMap(FileHeader::getExt, identity()));
     }