The GrokReader service includes a single property named Grok Expression, which the Reader uses to parse input lines. This approach requires the configured Grok Expression to handle all possible formats for input lines.
The GrokReader should be enhanced to support multiple expressions that the Reader can use when attempting to parse input lines. The Reader should follow the configured order of multiple expressions.
Support for multiple expressions could be configured using the property value itself, or through a file that could be referenced from an external location.
The implementation should maintain compatibility with the current GrokReader.