Why is this an issue?

JDK7 introduced the class java.nio.charset.StandardCharsets. It provides constants for all charsets that are guaranteed to be available on every implementation of the Java platform.

These constants should be preferred to:

Noncompliant code example

try {
  byte[] bytes = string.getBytes("UTF-8"); // Noncompliant; use a String instead of StandardCharsets.UTF_8
} catch (UnsupportedEncodingException e) {
  throw new AssertionError(e);
}
// ...
byte[] bytes = string.getBytes(Charsets.UTF_8); // Noncompliant; Guava way obsolete since JDK7

Compliant solution

byte[] bytes = string.getBytes(StandardCharsets.UTF_8)