fix(reporter): Do not take blank license texts

Recent ScanCode versions started to add a YAML front matter to license
files (also see b9c038e). This means that now license files are present
even in cases where ScanCode previously had no license text. Such files
now only contain the YAML frontmatter, and removing the frontmatter
makes them blank. Note that even online files like [1] are blank now.

Avoid using such files for license texts by adding a check whether their
contents are blank. This fixes an issue with the SPDX reporter which has
a check that `extractedText` for a `SpdxExtractedLicenseInfo` must be
non-blank.

[1]: https://scancode-licensedb.aboutcode.org/generic-cla.LICENSE

Signed-off-by: Sebastian Schuberth <[email protected]>

reporter/src/main/kotlin/LicenseTextProvider.kt

@@ -26,7 +26,8 @@ interface LicenseTextProvider {
     /**
      * Return the license text for the license identified by [licenseId] or null if the license text is not available.
      */
-    fun getLicenseText(licenseId: String): String? = getLicenseTextReader(licenseId)?.invoke()
+    fun getLicenseText(licenseId: String): String? =
+        getLicenseTextReader(licenseId)?.invoke()?.takeUnless { it.isBlank() }
 
     /**
      * Return a lambda that can read the license text for the license identified by [licenseId] or null if no license
@@ -35,7 +36,8 @@ interface LicenseTextProvider {
     fun getLicenseTextReader(licenseId: String): (() -> String)?
 
     /**
-     * Return true if a license text for the license identified by [licenseId] is available.
+     * Return true if a license text for the license identified by [licenseId] is generally available. Note that this
+     * does not necessarily mean that the text is meaningful (i.e. non-blank).
      */
     fun hasLicenseText(licenseId: String): Boolean = getLicenseTextReader(licenseId) != null
 }