On a campus already beset by claims of bullying and sexual harassment, a Hercules High School transgender student told police he was assaulted by three boys Monday while exercising his right under a controversial new law to use a bathroom that matched his gender identity. The attack was the second altercation involving a transgender student on the campus this school year and came only days after an overwhelming teachers’ vote of no-confidence in the school’s principal, partially spurred by complaints of a lack of safety on campus that had led to fights and arrests…