chore(spdx-utils): Remove superfluous case distinctions for equals()

The `is SpdxExpression` case covers `SpdxCompoundExpression`s and
`SpdxSingleLicenseExpression`s. As `SpdxCompoundExpressions` have at least
2 children, decomposition can never result in just a single element. This
leaves `SpdxSingleLicenseExpression` to handle, but these can only ever
by equal if they are of the same sub-type, which is already covered by
the first case distinction.

Signed-off-by: Sebastian Schuberth <sebastian@doubleopen.org>

Author: sschuberth

utils/spdx/src/main/kotlin/SpdxExpression.kt

@@ -525,14 +525,6 @@ class SpdxLicenseWithExceptionExpression(
     override fun equals(other: Any?) =
         when (other) {
             is SpdxLicenseWithExceptionExpression -> license == other.license && exception == other.exception
-
-            is SpdxExpression -> {
-                val decomposed = other.decompose()
-                decomposed.singleOrNull()?.let {
-                    it is SpdxLicenseWithExceptionExpression && it.license == license && it.exception == exception
-                } == true
-            }
-
             else -> false
         }
 
@@ -590,14 +582,6 @@ class SpdxLicenseIdExpression(
     override fun equals(other: Any?) =
         when (other) {
             is SpdxLicenseIdExpression -> id == other.id && orLaterVersion == other.orLaterVersion
-
-            is SpdxExpression -> {
-                val decomposed = other.decompose()
-                decomposed.singleOrNull()?.let {
-                    it is SpdxLicenseIdExpression && it.id == id && it.orLaterVersion == orLaterVersion
-                } == true
-            }
-
             else -> false
         }
 
@@ -639,12 +623,6 @@ data class SpdxLicenseReferenceExpression(
     override fun equals(other: Any?) =
         when (other) {
             is SpdxLicenseReferenceExpression -> id == other.id
-
-            is SpdxExpression -> {
-                val decomposed = other.decompose()
-                decomposed.singleOrNull()?.let { it is SpdxLicenseReferenceExpression && it.id == id } == true
-            }
-
             else -> false
         }