Location of Issue:
https://dev.java/learn/numbers-strings/string-builders/#stringbuilder-operations
Description:
In the section "StringBuilder Operations", at the arguments of the insert method:
"You can insert any primitive type or object at the given offset with one of the insert(int offset)..."
Suggested Fix:
"insert(int offset, Object obj)"
Not sure if it's intentional or if it's a mistake.