When org.spdx.utility.compare.LicenseCompareHelper.isTextStandardLicense().isDifferenceFound() is run on the official GPL-1.0 license text, it (incorrectly) returns true (i.e. the standard license was not matched). When I run org.spdx.utility.compare.LicenseCompareHelper.isTextStandardLicense().getDifferenceMessage() on it, I get:
Additional text found after the end of the expected license text starting at line #192 column #21 "end"
However the GPL-1.0 SPDX template does appear to (correctly) contain the text END OF TERMS AND CONDITIONS at this point (albeit in an <optional> block).
This was reproduced with Spdx-Java-Library v1.11 and SPDX license list v3.23.