org.apache.spark.status.api.v1.SimpleDateParamSuite has this assertion:
This test is fragile and fails when executing in an environment where the local default timezone causes EST to be interpreted as something other than US Eastern Standard Time. If your local timezone is Australia/Sydney, then EST equates to GMT+10 and you will get:
In short, SimpleDateFormat is sensitive to the local default TimeZone when interpreting short zone names. According to the TimeZone javadoc, they ought not be used:
Three-letter time zone IDs
For compatibility with JDK 1.1.x, some other three-letter time zone IDs (such as "PST", "CTT", "AST") are also supported. However, their use is deprecated because the same abbreviation is often used for multiple time zones (for example, "CST" could be U.S. "Central Standard Time" and "China Standard Time"), and the Java platform can then only recognize one of them.