Please, make sure, you write Boolean Operators in capital letters, otherwise the platform wouldn't catch them.
AND - logical operator, which assumes the presence of all selected conditions at once.
OR - logical operator, which assumes the presence of at least one of the conditions.
NOT - logical operator, which is used before a condition that will be excluded from the search.
"..." - quotation marks used to search for exact terms or phrases.
( ) - brackets define the order in which logical operators work. Used to create complex queries. When forming a string, make sure that there is a pair of closing brackets for each part of the query.
* - the asterisk is used as a replacement character for any number of letters at the end of a word.
With space: Java * ( Java Spring, Java 8 etc.)