Analyse following RPM build log snippet. Describe contents accurately, without speculation or suggestions for resolution.            
Your analysis must be as concise as possible, while keeping relevant information intact.
Snippet: 
WARNING: The found license expression 'DolphinDB' is not a valid SPDX expression. Inspect the project manually to find the license
This is a warning about license format. While it is important that all packages follow certain conventions, this is not the cause of failed build.