Use synchronized HashMap. (#1678)

While there is a performance impact here it is most likely extremely
minor. And dwarfed by the fact that it's causing a simple time series
query to needlessly fail.

Considering this isn't technically a functional change I'm not super
worried about the tests... there's also the problem of exactly how to
test it.... am going to keep thinking about it.

Author: MikeNeilson

cwms-data-api/src/main/java/cwms/cda/formatters/ContentTypeAliasMap.java

@@ -11,12 +11,12 @@
 import cwms.cda.formatters.annotations.FormattableWith;
 import org.jetbrains.annotations.NotNull;
 
-import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
 
 final class ContentTypeAliasMap {
-    private final Map<ContentType, ContentType> contentTypeMap = new HashMap<>();
-    private static final Map<Class<? extends CwmsDTOBase>, ContentTypeAliasMap> ALIAS_MAP = new HashMap<>();
+    private final Map<ContentType, ContentType> contentTypeMap = new ConcurrentHashMap<>();
+    private static final Map<Class<? extends CwmsDTOBase>, ContentTypeAliasMap> ALIAS_MAP = new ConcurrentHashMap<>();
 
     private ContentTypeAliasMap()
     {