question: @ Nullable public VirtualFile findFileByRelativePath ( @ NotNull @ NonNls String relPath ) { if ( relPath . isEmpty ( ) ) return this ; relPath = StringUtil . trimStart ( relPath , "/" ) ; int index = relPath . indexOf ( '/' ) ; if ( index < 0 ) index = relPath . length ( ) ; String name = relPath . substring ( 0 , index ) ; VirtualFile child ; if ( name . equals ( "." ) ) { child = this ; } else if ( name . equals ( ".." ) ) { if ( is ( VFileProperty . SYMLINK ) ) { final VirtualFile canonicalFile = getCanonicalFile ( ) ; child = canonicalFile != null ? canonicalFile . getParent ( ) : null ; } else { child = getParent ( ) ; } } else { child = findChild ( name ) ; } if ( child == null ) return null ; if ( index < relPath . length ( ) ) { return child . findFileByRelativePath ( relPath . substring ( index + 1 ) ) ; } return child ; }
target:  Finds file by path relative to this file.