JAVA

java no enum constant

Forget about the naming conventions for a bit and just name your constants as it makes most sense: enum PropName { contents, columnHeadings, ...}. This is obviously the most convenient.
Convert your camelCase input into UPPER_SNAKE_CASE before calling valueOf, if you're really fond of naming conventions.
Implement your own lookup method instead of the builtin valueOf to find the corresponding constant for an input. This makes most sense if there are multiple possible mappings for the same set of constants.